Dark Frontier (episode)
When Captain Janeway devises a plan to steal a transwarp coil from a damaged Borg sphere, the mysterious Borg Queen learns of the plan and uses this knowledge in an attempt to return Seven of Nine to the Borg by issuing her an ultimatum: rejoin the Collective or watch as Voyager is assimilated.

Summary

Teaser 
2375

A vessel has been detected by the Borg Collective and drones are activated aboard one of its ships. The drones are instructed to alter course to intercept the vessel. Inside a Borg ship drones immediately move from their alcoves and carry out the instructions. The Collective identifies the vessel: Federation Starfleet; ; 143 lifeforms. The drones are instructed to prepare for assimilation of the vessel.

The target vessel is the . The Collective states its usual hail: "We are the Borg. You will be assimilated. Resistance is futile". The image of Voyager is replaced by one of Voyagers bridge. Captain Kathryn Janeway stands with Commander Chakotay at her side. Behind them, at the auxiliary tactical console is Seven of Nine whom Janeway has asked to be present for her tactical expertise. She replies with a warning to the Collective to break off pursuit or Voyager will open fire. The Collective dismisses Janeway's threat and repeats that it is intent on assimilating Voyager, they cut off communication.

The Borg vessel closes on Voyager but it is neither a cube nor a sphere; instead, it is a probe. The two ships exchange fire. Aboard the probe, there are explosions as the deflector shields are disabled. The Collective instructs that they be regenerated and the weapons re-modulated when, suddenly, a Starfleet photon torpedo is transported into the vessel. A drone moves to disable it but as the drone is about to begin dismantling the torpedo it detonates, destroying the probe and all drones aboard.

On Voyagers bridge, Janeway and Chakotay watch the explosion on the viewscreen. Both seem disappointed, Chakotay asks what happened as the goal was to merely disable the probe. Seven of Nine explains that the torpedo detonated near the power matrix, causing a chain reaction in the probe's systems. Janeway asks about survivors and Lt. Commander Tuvok reports that there were none.

Janeway stares at the viewscreen for a moment then orders Chakotay to begin a salvage operation. The probe could have something they could use, such as weapons or possibly a transwarp coil. This is a key component of Borg supraluminal technology, allowing them to travel at speeds far greater than the Federation's standard warp drive. If they can modify it and their warp engines to work together, thousands of light years could be put behind them in mere days, taking years off their journey.

Act One 
Janeway and Chakotay enter Cargo Bay 2, where the debris from the destroyed probe is being studied. They walk around the debris, inspecting various components. Chakotay informs her that they have salvaged some useful components from the probe: power nodes and plasma conduits. Also, a transwarp coil was found amidst the debris field.

They go to see the coil and find Seven of Nine and  B'Elanna Torres examining it. Their report is disappointing as the coil is unusable. Seven explains to her that when a Borg vessel is critically damaged, all of its vital technology, such as its transwarp coils, self-destructs.

But Seven of Nine also has hopeful news from their salvage operation. She shows Janeway and Chakotay two Borg data nodes, one of which contains long range sensor telemetry, assimilation logistics and vessel movements in a thirty light year . This is vital information for Voyager as they can use it to avoid any further encounters with the Borg for a time. However, the unusable transwarp coil is a great disappointment and Janeway orders Seven to translate the node's data so the ship's computer can read it.

In astrometrics, Seven shows Janeway and Tuvok the translated tactical information. She reports there are three cubes on a course parallel to their own, nine light years distant which pose no threat. But Janeway points out a Borg sphere whose position is not far from them and asks Seven about it. Seven reports that the sphere is damaged from an ion storm and traveling at low warp. Janeway orders Seven to provide her with a detailed schematic of the vessel.

Janeway calls a meeting with the senior staff in the briefing room. She describes a plan: they are going to steal a transwarp coil from the damaged sphere. The plan is labeled "Operation Fort Knox", after the 20th century facility which, all through its existence, defeated all attempts at intrusion. Ensign Tom Paris helps by explaining the reference to the others present. Chief Engineer Torres talks about how useful even one coil would be in drastically shortening their journey time to the Alpha Quadrant.

Tuvok asks Janeway if she believes the sphere's defenses are low enough for them to do this. Janeway does believe this but she warns that the operation must be planned to the smallest detail. She reminds them that they cannot forget that they are dealing with the Borg. She proceeds to explain the plan in general terms: they will head for the sphere and use a diversion to allow an away team to beam aboard undetected. The away team will then steal the coil and return to Voyager with it. Chakotay recommends they create a holodeck simulation of the operation to practice it. Torres recommends they use a few "old Maquis tricks" she knows to mask their warp signature. Janeway agrees to both remarks and ends the meeting to begin preparations.

Act Two 
After the meeting, Janeway calls Seven into her ready room. She informs her that she has a specific assignment for her relating to the operation. She wants Seven to research the data logs of her parents, Magnus and Erin Hansen, for any information which could give them a greater tactical advantage against the Borg. These logs were retrieved the year before, among the remains of the Hansens' ship, the .

Seven of Nine begins to make excuses why the logs should not be consulted. She believes them to be irrelevant and flawed since her parents, despite all the knowledge they had gathered, were caught and assimilated. Janeway surmises, however, that Seven does not want to read them because they chronicle the events leading to her assimilation. But Janeway cannot afford to forgo the potentially invaluable tactical information contained in the logs and tells Seven that she will assign the task to Chakotay if she refuses. Seven informs the captain that, although reluctant, she will read the logs.

Seven is in her Cargo Bay 2 quarters, near her alcove, examining one of the Borg data nodes. Neelix enters with a large box full of PADDs. Seven irritably notes his tardiness and Neelix apologizes. He explains that cataloging the logs took much longer than he expected because of the amount of data including field notes, personal logs and bio-kinetic analyses. He sets the box down and quietly muses that she is fortunate to have so huge a reminder of her own parents. All he has left of his own parents is a faded holo-image. As he leaves to prepare the rest of the logs, Seven picks up one of the PADDs and activates it.

2350

Annika Hansen is playing with a model of a Borg cube. Magnus Hansen enters. He leads her to a couch, sits with her and explains to her that they will be leaving the next day to study the Borg. Annika is full of questions for her father: Do the Borg have kids? What do they look like? Are they friendly? Her father answers her questions as best he can.

Eight months later
Aboard the Raven, Magnus and Erin Hansen debate whether or not they should refuel before continuing onward. Magnus does not want to, insisting they are too close and if they stop now, they may as well return home. Erin questions what they would return home to as they have committed numerous felony violations: unauthorized deviation from flight plan, crossing the Romulan Neutral Zone, failure to obey direct orders to return. She expresses that she is of the opinion their colleagues obviously think they have gone insane. Annika enters from her bedroom, complaining that she cannot sleep.

The sensors sound an alarm, detecting massive subspace eddies. Magnus and Erin hurry to the main console and detect a ship their scans reveal that it is a Borg cube. They enter visual range and bring it up on the viewscreen. Magnus, Erin, and Annika stare at the cube as it scans them and their vessel. The cube does not alter course to intercept and instead it moves off. Magnus says that this confirms his theory how the Borg ignore anything living unless they consider it a threat, or a target for assimilation. They follow the cube, remaining well behind it.

2375
A hail from the bridge by First Officer Chakotay brings Seven back to the present. She acknowledges Chakotay's hail and responds. Coming off the turbolift onto the bridge she sees the the damaged Borg sphere on the viewscreen. Janeway orders Paris to match its course and speed, keeping ten million kilometers away. Seven is ordered to the auxiliary tactical console to scan the sphere. She reports that its weapons array is regenerating, but its deflector shields and transwarp drive are off-line. However both systems will again be operational in 72 hours. The crew has a window of 72 hours to execute the operation. Janeway orders double shifts and 24-hour simulation drills for the crew.

Act Three 
Captain Janeway, Seven of Nine, Tuvok, and Harry Kim quickly walk down a corridor on the Borg sphere, armed with phaser rifles. Chakotay, on Voyagers bridge, counts down from two minutes, keeping them informed of their remaining time. The operation is going well, but Chakotay warns them they are behind schedule. Drones walk around the sphere ignoring them. Janeway and Seven proceed to the transwarp chamber, while Tuvok and Kim go to sphere's shield generator. They plant spatial charges around the generator while Janeway and Seven position transporter pattern enhancers on the coil. When Kim and Tuvok detonate the charges the coil is transported to Voyager. Chakotay confirms they have the transwarp coil and the away team proceeds to the pre-arranged coordinates for beam-off.

But their time runs out. Chakotay informs them the two-minute period it takes for the Borg sensor grid to regenerate after being disabled has expired. Aboard the sphere, an alarm sounds as drones immediately stop, face the away team and advance. Tuvok fires and kills two drones coming towards him and Kim. Janeway and Seven are engaged with two other drones, but the Collective quickly adapts to the phaser setting. Janeway turns to go along another route, ordering Seven to follow but she is frozen in place.

Janeway calls back to her sharply and Seven of Nine snaps out of it, following her down the corridor. They arrive at the transporter coordinates, where Tuvok and Kim are waiting, and the four of them beam out of the sphere.

On Voyagers bridge, Paris reports to Chakotay the away team's successful return. Suddenly a contingent of drones appears on the bridge. Chakotay orders Paris to beam them off, but he cannot and the drones fan out and begin to advance on them.

Chakotay orders the computer to freeze both programs on both holodecks. It was all a simulation.

Chakotay demands an explanation from Paris. He replies that the drones must have piggybacked on Voyagers transporter beam. Chakotay hails Janeway and informs her that they retrieved the coil, but also some most unwelcome guests. Because the two-minute window before the sphere's sensor grid returns online is the maximum amount of time for the away mission, they have to cut their time on the sphere to under two minutes. Beaming into the transwarp chamber directly is considered, but Seven responds that the chamber is too heavily shielded. The away mission looks impossible, but Seven informs them that her parents were able to spend several hours at a time on a cube undetected. By consulting their logs, they may be able to explain how the Hansens were able to do this. Janeway orders her to find out and ends the simulation.

As Janeway and Seven walk along the corridor outside the holodeck, Janeway asks her about her freeze-up during the simulation stating that she cannot afford such an incident during the operation. Janeway asks Seven if she is able to take part in the away mission. Seven responds that the simulation unsettled her. The last time she was on a Borg vessel, she was a drone. Janeway wonders if she is pushing her too hard and fast, making her face her past by looking at her parents research and now having her on the away team. Seven insists she will be fine. Janeway hopes so, the next time it will not be a simulation, she tells her. Seven acknowledges her statement and walks off.

Seven prepares to read another batch of her parents' logs in her quarters. The doors open and Naomi Wildman, daughter of crewmember Ensign Samantha Wildman, enters. She complains to Seven that she is having nightmares and wants to stay with her, promising not to bother her. Seven agrees but as she continues her work, Naomi begins asking some oddly familiar questions about the Borg: Does it hurt to be a drone? Do the Borg have kids? Are they friendly? Distracted and worn down, Seven tersely orders Naomi to return to her quarters.

Naomi walks towards Seven and in a cold, hard voice states "Resistance is futile." A Borg implant emerges and spreads on her cheek.

Seven panics as she looks around her quarters and sees Borg drones stepping out of the shadows. She frantically hails security, but receives no answer. Instead, she hears an ageless, disembodied, female voice state "They can't hear you." Seven demands to know the voice's identity. "I am the Borg," it responds. The voice calls her by her full Borg designation: Seven of Nine, Tertiary Adjunct of Unimatrix 01, stating that she has become weak. Seven frantically tells herself that this is a dream that she is regenerating. The voice assures her that she is not in a dream. It explains how the Borg have accessed Seven's neural transceiver. The voice tells her that they know about Voyagers plan to invade the sphere stating that it will fail. Seven demands to know why the crew hasn't been assimilated if the Borg believe the plan to fail. The voice states that they have contacted her to make an offer: "Rejoin the Collective and we'll spare Voyager."

Seven is confused by this statement, as the only thing that set her apart from other drones was that she happened to have been chosen by the Collective to speak for the Borg during the events which had led to her de-assimilation. The Collective could easily have chosen any drone aboard that cube. () Seven asks why any effort would be taken to retake her when the Borg has since then assimilated thousands of new drones. The voice responds that they wish her to rejoin the Collective because Seven is "unique."

The voice and drones vanish. The cargo bay is normal again and Seven is alone.

Act Four 
2350
Three months after first encountering the Borg cube, the Hansens have followed it through a transwarp corridor it created, arriving behind it in the Delta Quadrant, the region of origin of the Borg. Magnus Hansen is aboard the cube, wearing a bio-dampener to remain undetected. The Raven itself is outfitted with multi-adaptive shielding to mask it from Borg sensors. Both technologies have worked magnificently, allowing them to follow Borg vessels and beam on and off them without detection.

Magnus reports back to Erin (who sits at the controls with Annika on her lap) that he is observing a badly-damaged drone, which the Hansens have dubbed "" as it goes to an alcove to regenerate intending to repairing itself. However two other drones, which they have dubbed """ and "Needle Fingers," arrive, deactivate the damaged drone and begin dismantling it. On the Raven, an alarm notifies Erin that Magnus' bio-dampener is almost out of power. She updates him, but he responds that he can stay on board for another minute.

2375
Seven shows the designs for the bio-dampeners to Tuvok and The Doctor in sickbay. She found the designs in her parents' logs and explains how these devices should solve the timing problem. Tuvok instructs The Doctor to manufacture four of them, one for each away team member.

After Tuvok leaves, The Doctor compliments the Hansens on their ingenuity. Seven responds that the Hansens were efficient. Thinking that she is warming up to them, he happily cites this as an important stage in her social development, and encourages her to think of it as an exploration of how she was raised, an important part of her Humanity. Seven angrily replies that her parents underestimated the Borg. She states that because of their arrogance she was forced to be raised as a Borg drone. She storms out of sickbay and goes into a corner, struggling to regain control of herself.

"Captain's Log, supplemental. "Operation Fort Knox" is ready to proceed. All departments are standing by, and I've given the order to begin at 0600 hours."

The away mission will begin at 0600 the next morning. But Janeway has made a change in the away team composition. She calls Seven into her ready room, and tells her that she has decided to replace her on the away team with Torres. She explains that if the sphere attacks, she will need someone with Borg expertise at tactical. Seven insists that she must be on the away team. She gives the excuse that they may encounter unexpected problems that only she can overcome. Janeway takes offense to the comment, thinking that Seven simply considers them not up to that task.

However, Janeway realizes that Seven is not being arrogant, only fearful of the success of the mission. Seven fervently tells her that, in the time she has been on Voyager, the crew has become her Collective. Their survival is important to her. She would do anything to prevent harm from coming to them… anything. She pleads with Janeway to be put back on the away team. Janeway reconsiders and places Seven back on the away team, telling her that she is very pleased with the remarkable progress she has made as an individual and a crewmember.

Act Five 
The Borg Collective detects a vessel and activates the drones manning the damaged sphere. They alter the sphere's course to intercept. The vessel is identified as a Federation Class 2 shuttlecraft with three lifeforms aboard.

The Collective does not instruct the drones to prepare for assimilation. The sphere resumes course. On Voyagers bridge, Torres reports this to Chakotay. The shuttle is the diversion part of the plan; when the sphere drops its shields to take it in to assimilate it, the away team beams aboard. But the Borg are not taking the bait. Chakotay informs Janeway, waiting in one of the transporter rooms on the platform with the other team members, Seven included.

Ensign Kim suggests having the shuttle fire a phaser shot at the sphere, but Seven responds that that would not work; they would simply destroy the shuttle as a perceived threat. Janeway gets an idea. She orders Chakotay to have the energy output of the shuttle's warp signature increased. He does so. With the increased warp signature, the Collective instructs the drones to prepare for assimilation.

On Voyagers bridge, Ensign Paris reports that the sphere has locked a tractor beam on the shuttle and is taking it in. The sphere's shields drop and the away team beams aboard, wearing the bio-dampeners The Doctor produced. They begin their separate operations of the away mission. Seven immediately stops and has a vivid vision of herself when she was a drone. She hears the voice she heard in the cargo bay. "Never forget who you are," it tells her.

Janeway, worried, touches her shoulder and asks if she is alright. She shakes herself out of it and follows her to the transwarp coil chamber. Tuvok and Ensign Kim place the spatial charges on the shield generator as practiced. Janeway and Seven plant the transporter pattern enhancers on the coil. Tuvok and Kim blow the generator and the coil is beamed off the sphere. Janeway and Seven quickly move toward the away team's beam-out coordinates.

Moving through the sphere towards the coordinates, Seven halts again. The disembodied female voice again beckons her to rejoin the Collective in order to spare Voyager. Janeway, realizing she is not behind her, turns and sees her standing, looking at her. Annoyed, she orders Seven to keep moving. Seven responds that she will not follow Janeway and wishes to return to the Collective.

Janeway firmly tells Seven she cannot let her do that. Seven responds that Janeway has no choice. Janeway aims her rifle at her, preparing to stun her and take her back to Voyager, to remain under guard in the sickbay or the brig until she regains her senses. She again orders her to keep moving. A force field appears between them, and two drones come up behind Seven. Seven pleads with Janeway to leave her. Chakotay hails and informs Janeway that the sphere is moving to intercept Voyager and that the away team must beam out in order that the ship is not assimilated. But Janeway does not move. She tells Seven she will not leave without her. Seven responds by telling her that if she does not leave, she will be assimilated. Janeway gazes at her for a moment then turns and runs towards the beam-out point.

The rest of the away team arrives at the coordinates, and Janeway hails Chakotay: three to beam out. Chakotay questions the number but Janeway orders him to energize. Once they are back on Voyager, Chakotay asks where Seven is and Janeway angrily replies that she had a change of heart. She orders a situation report and he responds that the sphere is altering course away from them. Torres reports that its transwarp drive is powering up. Janeway, even though she knows it is hopeless, orders Paris to follow it. In a glow of green, the sphere accelerates to transwarp and races away in the blink of an eye.

Seven is led by two drones through the corridors of the sphere. The sphere itself drops from transwarp into an incredible sight: an immense Borg complex. Structures interconnect with each other in a web so huge that it seems to take up an entire sector. The sphere moves toward a hatch on one of the main structures. The hatch opens and the sphere disappears inside.

As Seven and her drone "guards" enter through a spearhead-shaped door they stand in a large room with a wide, slight raised platform situated in the middle. Above the platform, a head and its upper torso descend on a lift from above. The head appears to be that of a humanoid female alien. Descending, the head smiles a little. As the head and upper torso approach the floor, a disassembled black mechanical body, composed of the rest of the torso and limbs rises from the floor. After the two parts of the Borg are attached, the body slowly walks up to Seven.

Seven stares at the Borg as it descends from the platform. She realizes that this is the origin of the disembodied voice she had heard.

Her parents had a name for this type of Borg.

The Borg Queen.

"Welcome home," the Queen tells her.

Act Six 
The Borg Queen walks slowly around Seven, appraising her new appearance, noting how the individuals on Voyager have "remade her into their image" by removing her Borg features and giving her back hair and clothing. Seven sarcastically responds that she expected re-assimilation, not conversation. The Queen notes her sense of humor and comments that the last two years must have been remarkable for her. She repeats what she told her in Voyagers cargo bay: she is unique.

Seven wonders aloud that her experiences on board Voyager are why the Collective wanted her back, to "add to their perfection." The Queen responds that this was Seven of Nine's mission all along. The Borg purposefully let Voyagers crew take Seven. Surprised, Seven demands that the Queen explain herself, but she receives no answer. The Queen instead offers her a chance to regenerate in an alcove that has been adapted for her. She lets Seven know that after her regeneration they will speak further on her capture.

Aboard Voyager, in Cargo Bay 2, crewmen clear away the debris from the Borg probe. The debris was stripped of useful components and they will melt the components so that the polytrinic alloys can be extracted. As Janeway and Chakotay supervise the cleanup, she expresses her frustration at trying to understand Seven's actions. She cannot understand why she chose to rejoin the Collective now. Chakotay theorizes that Seven had been planning this all along, he reminds her that Seven threatened to betray Janeway after they had first severed her from the hive mind two years earlier. Janeway doesn't believe him and tells him that Seven had come to see Voyager as her Collective.

Neelix, who is helping with the clean-up, comes up to them and asks Janeway what to do with Seven's alcove. With her gone, logically the alcove, which uses a lot of power, has no function and should be shut down. Janeway tells him no and he goes back to work.

In her ready room, Janeway sits at her desktop monitor, reviewing sensor logs from the day before their operation to steal the transwarp coil from the damaged sphere. She has a hunch that the Borg somehow influenced Seven to rejoin them and believes the logs have evidence of that. As she works, Tuvok arrives and explains that "a member of the crew" has requested an appointment with her. Janeway is about to refuse due to being so busy, but then sees Naomi Wildman peeking out from behind Tuvok and relents, allowing her in. Naomi has come to see her with a plan she has designed to find Seven. Janeway looks at it and tells her that it would not work but she commends Naomi for her initiative. Before Naomi leaves, she asks Janeway if they're going to rescue Seven, and Janeway assures her that a good captain never abandons a member of the crew; they're not giving up on Seven. The computer then beeps letting Janeway know that it has finished analyzing the sensor logs and has found an anomaly. Janeway and Naomi look at the monitor as it shows that Borg communication signals were directed towards Cargo Bay 2.

In the Borg Unicomplex, Seven awakens from regeneration to find her vision has returned to that of the Borg. The Borg Queen informs her that her brain's sight-controlling region has been re-enhanced with Borg technology with the addition of a neural processing adjunct. Seven fearfully and angrily demands its removal. The Queen responds that Seven prefers to remain small but Seven replies that she prefers to remain unique.

The Queen reassures her that this is not what the Borg want, they want her individuality intact. Seven returns to her initial question asking why the effort was made to capture her. The Queen replies that they need her for her individual, Human perspective. Seven does not understand as they have already assimilated her memories and could need nothing more. The Queen's answers that they want her to help them finally succeed in doing what they have twice tried and failed to do: assimilate Humanity.

Seven adamantly tells her she will resist. The Queen responds that she knows this.

The chamber shakes and Seven demands to know what is happening. The Queen informs her they are off to assimilate a species. She shows Seven a holo-projection of the targeted planet with a population of 392,000 and the inhabitants whom the Borg refer to as Species 10026. Their presence is not required, she tells Seven, but she deems the experience necessary to remind her of what it means to be Borg. Seven looks at the projection fearfully. The Queen notices her fear, remarking that she is experiencing compassion, a Human emotion.

A hatch opens in a structure in the Unicomplex, and a diamond-shaped vessel emerges, carrying Seven, the Queen, and attendant drones. It moves out of the Unicomplex to rendezvous with two Borg cubes. The three vessels head off for Species 10026's planet. Aboard the diamond, Seven continues gazing at the projection in sympathetic terror.

Act Seven 
2350

Aboard the Raven, Magnus and Erin Hansen examine a regenerating new drone that they have beamed over from a cube they have been shadowing. They ascertain the species it was a Ktarian (Species 6961). The drone's infrastructure was made of titanium, meaning it was a tactical drone. To their surprise they check its previous designation (Three of Five, Tertiary Adjunct of Unimatrix 1) and realize it used to work close to the Borg Queen.

As Annika watches with interest, they decide to put a tracking device on the drone. If it should ever return to Unimatrix 1, they could get the opportunity to study the Queen herself. An alarm alerts them that its regeneration cycle is almost complete and they quickly beam it back to its alcove aboard the cube. While Erin and Annika eat, Magnus inspects the drone's downloaded cranial transceiver logs, looking for communication signals from the Queen.

2375
In Janeway's ready room, Chakotay reports that a comparison between the signals Magnus Hansen recorded in 2350 on the Hansens' logs and those that Janeway discovered being sent to Seven in Cargo Bay 2 matched. Seven was indeed getting communication from what he calls "this… Borg queen" (the existence of such a thing is unknown to Starfleet at the time Voyager was pulled into the Delta Quadrant, since the Hansens never returned home with their data and the Battle of Sector 001 had just recently occurred).

Janeway notes that, whatever the nature of this "queen", she obviously is very influential, having made Seven turn herself over to the Collective the day after contacting her. Chakotay wonders if Seven was instructed to return to the Collective, but Janeway recalls her conversation with Seven before the mission when Seven insisted that she had to be on the away team and go aboard the sphere or the mission would fail. Janeway tells Chakotay that Seven had seemed very afraid, as if there was something she knew that she could not tell. In hindsight, Janeway intuits that the Queen didn't instruct Seven per se; she threatened her with the assimilation Voyagers crew if she did not turn herself over to the Collective. Janeway orders Chakotay to compile a list of every available technology the Hansens developed to track the Borg. Seven saved them from the Collective by turning herself over, now it's time to return the favor.

Janeway addresses the entire crew from the bridge outlining the mission: a long-range tactical rescue. During her speech various preparations around the vessel are taking place. Torres is equipping the  with the recovered transwarp coil. An away team consisting of Paris, Tuvok, The Doctor, and Janeway will go after the sphere that took Seven through transwarp space using tracking technology Chakotay found in the Hansens' logs. The Hansens' multi-adaptive shielding will mask the Delta Flyer from Borg sensors, and narrow beam transporters will allow the away team to board the sphere. Chakotay will keep Voyager at the threshold of the Delta Flyers transwarp conduit to offer tactical support against any pursuing Borg ships on the Delta Flyers return. She ends her address with the following exhortation: they will be looking for one individual among thousands of drones. "But she is one of us," she finishes, "and I am not about to let her go." She looks at the expectant bridge officers. "Let's get started."

The Delta Flyer takes off and on Janeway's order, Paris brings the transwarp coil online and, in a flash of green, the shuttle goes to transwarp, heading in the direction the sphere was traveling. Tuvok detects the sphere's residual transwarp signature, and Janeway orders Paris to follow it.

The Borg Queen's vessel and the two escort Borg cubes arrive at the Species 10026 planet to begin assimilation. The Borg Queen manipulates Seven into suggesting a way to adapt to Species 10026 weapons fire, a modulating phaser pulse that can penetrate Borg deflector shields. Initially Seven refuses to provide a strategy stating, "You are the Borg, you tell me." The Queen does not respond; instead, she lets the aliens bombard the Borg diamond until Seven becomes alarmed. She then calmly looks at Seven and repeats her question: How does she propose they adapt? Not wanting to die, Seven instinctively suggests a strategy. The Queen smiles, agrees with Seven's assessment and communicates it to the drones for implementation. Immediately the weapons' fire is rendered completely ineffective.

Pleased, the Borg queen instructs Seven to assist in the primary assimilation chamber. However, seeing Seven's terrified reaction, she changes her mind, thinking aloud that perhaps she is pushing her too hard. She instructs her to assist in repairing their shield generators instead.

Seven walks unsteadily through the corridors, going to her assigned task. Around her, captured members of the humanoid species are escorted by drones to assimilation chambers. Bloodcurdling screams ring out from the direction of the assimilation chambers. Fearfully, she reaches a panel and, trying her best to shut out the screams, starts repairing the generators. An explosion knocks her down, and as she attempts to stand up, two drones come behind her and pick her up roughly. She struggles as one brings a Borg prosthetic to her face. But it simply passes it over a cut she sustained, healing it. They release her and continue on their way.

A small group of aliens pass by, on their way to a chamber, escorted by drones. Suddenly a male among them tries to run away past her. Instinctively, she grabs his arm, stopping him. She immediately realizes what she is doing and releases him. Her realization comes too late, as one of the drones returns for the male. It seizes him and mercilessly plunges its assimilation tubules into his neck. He freezes, trembling in agony. Black lines radiate over his head and neck, as millions of Borg nanoprobes flood his system, beginning his assimilation. Seven watches, horrified. She stumbles back, shuddering and hyperventilating.

She then notices that she is just outside an assimilation chamber and enters. Inside, a few of the aliens watch helplessly as a drone works on assimilating one of them with exact precision. Another drone stands by watching. The victim is lying on a platform and his right arm has been severed while an attachment for the prosthetic replacement the drone is about to install is on the stump.

The second drone leaves the chamber to go and carry out a repair. As soon as it has gone, Seven immediately comes up behind the drone working on the victim and deactivates it. She lifts the victim up off the platform and orders the others to assist her. They stare at her in confusion and alarm. She tells them sharply that she is not Borg; she will help them escape. "Assist me!" she orders. They take their comrade as Seven instructs them what to do. One of their ships is nearby. It is heavily damaged and the crew is dead, but the propulsion system still works. She will transport them aboard; they must remain there until the Borg leave, and then they must flee on a heading she gives them. They nod understanding, and Seven goes to a console and beams them out.

Seven re-enters the Borg Queen's chamber. The queen is pleased: assimilation is complete. Seven angrily asks if the three hundred thousand individuals who have just been destroyed should be congratulated as well. They should be indeed, the Borg queen responds; they have been delivered from chaos into order. Seven sarcastically comments that she should use those words next time instead of "Resistance is futile", they may actually get some of the victims to volunteer. The Queen responds that Seven is simply hiding behind sarcasm in order to not acknowledge the pleasure of a new species being added to the Collective, a pleasure which she fully remembers. Stop resisting, the Queen urges her, revel in it.

Seven pauses. She can indeed feel it. But the sickening horror of what she has seen makes her reject it. Instead, she remembers how she used to be part of such atrocities herself. Full of guilt, she tells the Queen that she will not take pleasure in the destruction of a race. The Borg Queen is again disappointed and angered by Seven's reaction. Impatiently, she insists that her feelings of guilt, compassion, and empathy are irrelevant. Seven strongly disagrees, arguing that they are relevant to her. This further angers the Queen as there is no me, she insists; there is only us.

Then the Queen's head tilts to one side as she detects the ship containing the unassimilated aliens. It appears on her chamber's viewscreen and she asks Seven what should be done with it. Seven calmly and coolly tries to brush off the interrogation with subterfuge, saying that the ship contains only four aliens and would be a waste of Collective resources to capture and assimilate them, but the Queen will not have any of it, seeing through Seven's deception. She proclaims harshly that if one of Species 10026 escapes, then the species itself remains unassimilated. As they watch, a cube intercepts the ship and seizes it in a tractor beam. Seven watches, close to tears. She begs with the Queen to release them.

"I'm sorry this lesson has to be so painful for you," the Borg Queen tells her with false sympathy, "but you are a difficult pupil." She again urges Seven to abandon her Human emotions. "They are the cause of your pain," she insists. Seven continues to plead with the Queen for the survivor's release. The Queen looks at her impatiently and releases them. The cube releases the ship from its tractor beam and the alien ship speeds off to safety. Seven is dumbfounded by this unexpected action and remarks, "I thought compassion is irrelevant." The Queen acknowledges Seven with an intent gaze but gives no explanation.

Act Eight 
2350
The Raven flees at maximum warp. As Magnus explains in his log entry, a subspace particle storm knocked their multi-adaptive shielding off-line, leaving them exposed to Borg sensors. It was only off-line for 13.2 seconds, but that was enough; the Borg detected them and perceived them as a threat. Now they flee desperately from a Borg cube closely pursuing them. Although the Hansens have masked the Ravens warp drive signature, the cube still pursues them. Annika lies in bed, frightened, listening as her parents loudly discuss what to do. Erin points out a Mutara class nebula three light years away as a hiding place, but Magnus rejects it, saying its particle density is too high and their hull would rupture. Erin argues that they have no time to look for anything else. Annika calls for Magnus and he goes and comforts her. A transwarp conduit appears 2.3 light years away; a cube is preparing to assimilate.

2375
On the Delta Flyer, The Doctor pitches an idea to Captain Janeway to send a message to Seven through her interplexing beacon. Janeway approves and asks The Doctor to try once they reach their destination. Ensign Paris reports he has found the sphere, located two hundred light years from their position. Janeway orders him to head for it and orders Tuvok to raise the multi-adaptive shielding.

They drop out of transwarp and find themselves in the Unicomplex. The Humans and The Doctor are awestruck at the incredible size of the structure. Tuvok scans trillions of Borg lifeforms on it. A cube comes toward them but passes harmlessly, an indication that their multi-adaptive cloak is working. Janeway orders Paris to head into the Unicomplex and Tuvok begins scanning for Seven.

In her chamber, the Borg Queen makes a decision, it is time for Seven to serve her purpose. She informs Seven about a new mode of assimilation they have developed, for "highly-resistant species", surreptitious as opposed to direct assault: an assimilation virus. Seven is confused as she has no knowledge of this technology, having left the Collective before it was developed. The Queen tells her that her knowledge of the species they had in mind when designing it is invaluable. She brings up a holo-image of that species: Species 5618 – Human.

As Seven listens in shock, the Queen explains how the virus works. The virus is designed to infect every lifeform on a target planet, assimilating the planet's life slowly. By the time the population realizes what is happening, half of their population will be drones. Seven comes to the realization that the Borg are planning to release this virus into Earth's atmosphere. She tries to raise the objection that such a method would be inefficient, as it would take many years to yield results. The Queen merely responds that they have waited this long and the Collective can wait the required period. She gives Seven the job of programming the nanoprobes.

Seven flatly refuses to be part of Humanity's destruction. The Queen responds by reminding her of the thousands of assimilations she had been part of as a drone and how this is no different. After Seven still voices her refusal, the Queen again loses patience. They all came from "lesser species"; she herself came from Species 125. But that is irrelevant, she asserts, as they are Borg. "I am an individual!" Seven responds. The Queen's patience begins to wear thin. She explains that this is the purpose they require Seven for and she will fulfill it. She threatens Seven to either comply or be re-assimilated. To emphasize the threat, she has drones converge on her. But Seven stands her ground and defiantly tells the Queen to proceed if she wishes.

The Queen sees that threats will not work. Instead, she tries even more intense psychological manipulation. The Queen and the drones continue to close in on Seven as she backs away. The Queen tells Seven that she is torn between her desire to return to the Collective and her loyalty to the Voyager crew. She tries to comfort Seven with the expectation that all of her grief, all of her guilt, remorse and compassion will become irrelevant once Humanity is assimilated. Seven looks around at them fearfully. The Queen demands her to forget Voyager as they "were never your Collective." Seven stands her ground and rebelliously states that she is Annika Hansen – Human.

The Queen smiles and tells Seven that she remembers Annika but wonders if Annika remembers someone else. A drone steps forward and a horrified Seven recognizes who it was immediately – her father, Magnus Hansen. The Queen, sensing that Seven's resistance is weak, soothingly tells her, "Your family's here. You're here. Be one with us again." It works and Seven begins to give in to the Queen.

But then Seven hears the voice of Captain Janeway, urging her to hold on, they are coming. "Captain…" Seven whispers loudly enough for the Queen to hear her. "What did you say?" she asks sharply. Seven realizes her blunder and tries to say it was nothing, but the Queen does not believe her. She seizes her face and through the hive mind probes her thoughts finding the com link set up by The Doctor.

Act Nine 
On board the Flyer, Janeway and The Doctor discover that their com link to Seven is suddenly being blocked, indicating that the Queen knows they are coming. Tuvok reports he has found Seven's location just 600 kilometers away. Janeway orders Paris to head for the location. In her chamber, the Queen comments that although Janeway's com signal originated close by, they cannot detect her vessel. But she understands why this is so as they must be using the Hansens' multi-adaptive shielding. However, she notes, they assimilated that technology, therefore they can adapt to it quickly and easily.

Paris tensely reports a cube has altered course to intercept them, meaning that they have been detected. Janeway immediately orders re-modulation of the shielding. This works, but she knows they cannot fool the Borg sensors forever. They have to hurry. Tuvok reports that Seven is in a large chamber but he cannot get a transporter lock at their current distance. Janeway orders Paris to take them in closer. In her chamber, the Borg Queen attempts to use deception to dash any hope of rescue, telling Seven that the ship has been captured. However, Seven immediately knows she is lying as she is connected to the hive mind. As Seven once told Janeway, Borg make lousy liars; they cannot practice deception, as the hive mind makes it impossible. Seven tells this to the Queen who is greatly angered by being reminded of this.

The Flyer approaches the superstructure containing the Queen's Chamber and Paris reports it is too heavily shielded for the transporter to lock onto Seven. Janeway orders Tuvok to equip the newly-made bio-dampeners and accompany her into the structure. She orders Paris to target the chamber with the Flyers weapons he asks for clarification, very concerned. "Won't you be down there?" "Do it" she insists and he acknowledges. Janeway and Tuvok beam onto the superstructure, armed with phaser rifles. Their bio-dampeners work as they are undetected by the various drones while they move down a corridor.

But security is heightened and force fields go up along the corridor. These fields do not block drones, only non-Borg. They watch as a drone walks through one and Janeway gets an idea ordering Tuvok to give her a subdermal bioprobe.

On the Flyer, alarms alert Paris that the vessel's shielding is again being adapted by the Borg. Three cubes start converging on the shuttle. He quickly re-modulates their frequency and waits. In her chamber, the Borg Queen watches the viewscreen with great annoyance as the Flyer vanishes once again. Seven watches as well. "You underestimate them," she tells the Queen with satisfaction. The Queen bitterly remarks that it is time for a more aggressive approach. The Flyer is suddenly rocked by Borg weapons fire as the approaching cubes blindly fire in the vicinity of its last known position. Aboard, Paris tensely bobs and weaves the shuttle to avoid the blasts.

Back near the Queen's Chamber, Janeway and Tuvok walk up to a regenerating drone and Janeway implants it with the subdermal probe and has Tuvok wake it. Once activated, the drone walks up to a force field, pauses and then walks through. Janeway reads the force field's modulation and adjusts her bio-dampener to be compatible in order to walk through the fields herself. As she does so however, the field overloads her bio-dampener making her detectable by the Borg sensor grid. She quickly orders Tuvok to disable the shields around the chamber and hurries forward.

Aboard the Flyer, Paris realizes that his time is up; the Borg are now adapting to the shielding and sensing the ship no matter how fast he changes the frequency. The familiar, monotonous hail comes through: "We are the Borg. You will be assimilated. Resistance is futile". In her chamber, the Borg Queen speaks the words, AS the Collective.

Anguished, Seven charges at the Queen, her arm raised to strike her down, but the Queen turns and seizes her arm with hardly an effort. Seven struggles, futilely. The Queen tells Seven that retrieving her was a waste of time. "We believed you would be an asset to us. We were wrong," she tells her, scornfully adding that she has become weak.

"Don't listen to her, Seven," a voice says from the doorway. They turn to see Captain Janeway standing at the door. She walks in slowly, rifle pointed at the Queen, looking directly at her. Drones converge around Janeway and she warns the Queen to call them off or be destroyed. The drones stop. The Queen matter-of-factly tells her that her weapons are useless. Janeway disputes that, replying that her tactical officer is disabling the room's shields and her ship's weapons are targeted on the chamber. The Queen observes that she and Seven will be killed along with her.

Janeway responds that death is better than being one of them. The Queen tests her resolve by ordering the drones to resume their convergence on Janeway. Janeway calmly orders Paris to fire on her command; upon seeing that Janeway is not bluffing, the Queen again halts the drones. Paris reports that the attacking cubes have withdrawn. She orders him to beam her, Tuvok, and Seven out of the chamber. Suddenly, the lighting and shadows shift within the chamber. Paris reports that a dispersal field has gone up around them and he cannot beam them out.

Janeway turns to Seven and orders her to shut the field down. The Queen, though, attempts one last appeal to the Borg Seven used to be. She tells her not to listen to Janeway. "She's poisoned your thoughts long enough," she says sharply. Janeway simply makes her instruction to Seven a direct order. The Queen tries to counter by telling Seven that one order and one voice is "insignificant".

Seven looks at the Queen and then at Janeway. Attempting to reconcile who she was and who she is now, her inner battle is finally quelled. She moves to a console and plunges in her assimilation tubules. 

The field drops as the Queen furiously glares at Seven. Janeway smiles and orders Paris to energize, but then the Queen tilts her head and the lights and shadows suddenly shift again. Paris reports the field is back up. She looks at Seven and Janeway with contempt. Drones begin converging on them both. The Queen orders them assimilated. The drones close on them mercilessly.

Seven, however, informs Janeway that there is a power node directly above the Queen. If it is destroyed, the Queen's interface with the dispersal field will be broken. The Queen's head whips around to face her with a shocked, accusing glare.

"Our thoughts are one," Seven reminds her with a satisfied sneer.

Janeway wastes no time and immediately destroys the node with a blast from her rifle. She and Seven disappear from the chamber in the Flyers transporter beam. The Queen watches, her eyes full of fury.

Act Ten 
Upon beaming back onto the Flyer, Janeway welcomes Seven back to the crew. The Doctor runs a quick scan and finds Seven has not been in any way re-assimilated. She joins Tuvok at tactical and the Delta Flyer speeds away from the Unicomplex. Two cubes quickly follow the ship and are joined by the Borg Queen's vessel. On Janeway's order, the Flyer jumps to transwarp. Only the Borg Queen's vessel does the same – the cubes stay at the Unicomplex.

In transwarp space, the diamond fires on the Flyer, damaging its port warp nacelle. The shuttle begins to rapidly lose energy and Paris reports that they will drop out of transwarp in under a minute. Janeway orders rerouting of power from life support to the engines: better to suffocate than vaporize.

On Voyagers bridge, Torres, at tactical, reports to Chakotay that a transwarp conduit is opening 30,000 kilometers off the port bow – the Flyer is returning. Chakotay orders battle stations. In the conduit, the diamond tries to catch the Flyer in a tractor beam, but Seven deflects it. Paris counts down the time until they return to normal space where Voyager is positioned.

As the Flyer drops back into normal space, Janeway hails Voyager and informs Chakotay of the Borg vessel closely pursuing them. Chakotay gets an idea and he orders Torres to fire a full spread of photon torpedoes at the conduit's threshold. The resulting explosion would conversely implode the conduit for distance of at least a light year, destroying anything inside it for that distance. Torres does so and as the torpedoes detonate, massive space-transwarp space explosions cause the effect that Chakotay desired. Janeway hails Voyager and Chakotay informs her of the action taken. They seem to be home free, and she orders him to clear the Flyer for docking.

But then a shocked Torres reports the appearance of a large number of Borg signatures coming from the conduit. Neither she nor Chakotay can understand, as they were certain the conduit was collapsed. Chakotay tensely informs Janeway and orders battlestations and weapons ready. He and the bridge officers watch as the conduit opens, but that comes out is debris from the destroyed Borg Queen's vessel. They breathe a collective sigh of relief.

Janeway records in her log that the stolen transwarp coil gave them twenty thousand light years of service before giving out; they are now a good fifteen years closer to home. She enters Cargo Bay 2 and finds Seven at a console working, despite orders from The Doctor to regenerate for at least 48 hours. She is downloading Borg tactical data into the computer's database. She explains that she acquired a vast amount of data during her time at Unimatrix 01, connected once again to the hive mind. This data may prove useful in any future encounters with the Borg. Janeway approves.

But there is something on Seven's mind. She tells Janeway that she betrayed them and threatened them with assimilation and still they came back for her. She had not expected that course of action at all. Why did they do it? Janeway smiles at her and responds that she apparently still has much to learn about Humanity. She tells her it is time to regenerate; she has to follow The Doctor's orders.

"When I am finished," Seven replies.

"No," Janeway responds, her smile widening, "now."

Seven smiles back as she goes to her alcove and installs herself. As the regeneration cycle begins, she closes her eyes serenely. Janeway looks at her fondly and wishes her sweet dreams.

Log entries 
 Field notes, USS Raven

 "Captain's Log, supplemental. Operation Fort Knox is ready to proceed. All departments are standing by and I've given the order to begin at 06:00 hours."

 "Captain's Log, Stardate 52619.2. We got another twenty thousand light years out of the transwarp coil before it gave out. I figure we're a good fifteen years closer to home."

Memorable quotes 
"Vessel identified: Federation Starfleet, Intrepid-class, 143 lifeforms. Prepare for assimilation."
 - Borg Collective, sizing up Voyager

"We are the Borg. You will be assimilated. Resistance is futile."
"Break off your pursuit or we'll open fire."
"Irrelevant."
"Is it? You've scanned our vessel. You know we can match your firepower."
"You will be assimilated."
 - Borg Collective and Captain Janeway

"I don't know about the rest of you, but I feel lucky today."
 - Captain Janeway

"Now this is how I prefer the Borg: in pieces."
 - Captain Janeway to Commander Chakotay, looking at the Borg debris in the cargo bay

"Captain! Don't touch that!"
"What is it?"
"I don't know, but a few minutes ago it was crawling around on the floor."
 - Ensign Kim and Captain Janeway, speaking about a sphere-shaped piece of salvaged Borg technology

"Better safe than assimilated."
 - Chakotay

"Maybe I should go to red alert and get it over with."
"Commander?"
"You're about to drop one of your bombshells."
"Now what makes your say that?"
"The way you fiddle with your combadge. You it everytime."
"Well, I'll have to keep an eye on that."
 - Chakotay and Janeway

"It's impossible to offend a mindless drone."
 - Seven of Nine 

"I don't know about you, but I'm glad to be back on Voyager. Borg vessels make my skin crawl."
"It was a holodeck recreation"
"Close enough."
- Janeway and Seven of Nine

"When the New World Economy took shape in the late 22nd century, and money went the way of the dinosaur, Fort Knox was turned into a museum. A couple of Ferengi tried [to break into it] about 10 years ago, but other than that it is impenetrable."
 - Tom Paris

"I am the Borg. Seven of Nine, Tertiary Adjunct of Unimatrix Zero One, you've become weak."
"This is a dream. I'm regenerating."
"I assure you, it's not a dream. We've accessed your neural transceiver. Our thoughts are one. We know about Voyagers plan to invade the Sphere. It will fail."
"If that's true, then why haven't you assimilated them?"
"We've come to make you an offer. Rejoin the Collective and we'll spare Voyager."
"Why me?"
"Because you are unique."
 - Borg Queen and Seven of Nine

"I'm not leaving without you!"
"Then you will be assimilated!"
 - Captain Janeway and Seven of Nine – 

"How do you propose we adapt?"
"You are the Borg; you tell me."
 - Borg Queen and Seven of Nine

"They left behind their trivial, selfish lives, and they've been reborn with a greater purpose. We've delivered them from chaos into order."
"Comforting words. Use them next time instead of 'Resistance is futile.' You may elicit a few volunteers."
 - Borg Queen and Seven of Nine, on the assimilation of 300,000 new drones

"There are three things to remember about being a starship captain: keep your shirt tucked in, go down with the ship, and never abandon a member of your crew."
 - Captain Janeway, to Naomi Wildman

"You believe that Voyager liberated you from the Collective. Did you really think we would surrender you so easily?"
"Explain."
"You must be tired. It's time to regenerate. We've adapted an alcove just for you. Go. It will help order your thoughts. When your cycle is complete, we will continue our conversation. Comply."
 - Borg Queen and Seven of Nine – 

"My visual cortex... it's been altered."
"That's because we've enhanced it with Borg technology. You've seen through Human eyes long enough. It's a neuro-processing adjunct designed to increase your synaptic efficiency."
 - Seven of Nine and Borg Queen

"You're much too valuable to us with your individuality intact. But you've left Humanity behind. Try to abandon their petty emotions as well. Fear, anger, vanity. They've corrupted you, but the damage can be repaired."
"You've expended significant resources to capture me. Why?"
"Isn't it obvious? You're going to help us assimilate Humanity. We failed in our two previous attempts to assimilate Earth, and we won't succeed the third time unless we understand the nature of their resistance. We want you to be our eyes. Let us see Humanity."
 - Borg Queen and Seven of Nine

"While I was regenerating, you assimilated my memories."
"Our thoughts are one."
"Then you already possess all of my knowledge. What more do you want?"
"You are the only Borg that has ever returned to a state of individuality. We want to keep you exactly the way you are. Otherwise, you would lose your Human perspective. We don't want another drone. We want you."
 - Seven of Nine and Borg Queen – 

"Re-route power from life support."
"Captain?"
"I'd rather suffocate than vaporize, do it!"
 - Captain Janeway and The Doctor, while under attack from The Borg

Background information

Story and script 
 This episode's origin was similar to that of the third season outing , in that – when the writing staff of  were faced with the challenge of devising a show for the February rating sweeps period – the writers thought of the Borg. However, this idea was not an immediate one. Co-writer Joe Menosky offered, "We were heading into sweeps […] But we had no idea what we were going to do." (Cinefantastique, Vol. 31, No. 11, p. 32)
 The episode had the working title "Untitled Borg".
 The scale of the episode was influenced by the first airing of the fourth season two-parter  and . Joe Menosky reflected, "Because of the success of airing 'The Killing Game' in a single night, the network and the studio were really interested in doing a movie." (Cinefantastique, Vol. 31, No. 11, p. 32)
 Fellow co-writer Brannon Braga also wanted the episode to be, in his own words, "a big event" and the motion picture , another production that featured the Borg and a Borg Queen, provided an example that the writers were interested in attempting to surpass. Braga explained, "I really felt we needed something spectacular for February sweeps […] To do a Borg movie, telefilm, or whatever you want to call it, we had to outdo First Contact. The space battles and the Queen had to be more elaborate." (Cinefantastique, Vol. 31, No. 11, p. 32) Braga also said, "When we decided, 'Let's do something different; let's do a two-hour telefilm,' that made us rise to the challenge, and we did 'Dark Frontier'." ()
 It was Brannon Braga himself who crafted the episode's plot. He recalled, "We had all these different storylines laying around having to do with the Borg. I just cobbled them together late one night and we had 'Dark Frontier'." Joe Menosky remembered, "Brannon wrote this amazingly complete story memo that had everything." (Cinefantastique, Vol. 31, No. 11, p. 32)
 The inspiration for the backstory of the courageous Hansens – Magnus and Erin Hansen – was the history of gorilla specialist . (Cinefantastique, Vol. 31, No. 11, p. 34)
 In their effort to turn out an exceptional script, the writers worked for long hours on the teleplay. ()
 Brannon Braga enjoyed scripting the scenes that include the Borg Queen and Seven of Nine. He noted, "It was fun to write the banter between [Seven] and the Borg Queen." (Cinefantastique, Vol. 31, No. 11, p. 34)
 Brannon Braga also deliberately left several questions unanswered, such as the fate of Erin Hansen and the possibility that the Borg planted Seven of Nine to act as a spy on Voyager. Regarding the latter issue, Braga admitted, "I wanted people […] to ask that very question. The Queen may have done that; we'll never know. One of those tantalizing tidbits that the fans enjoy […] I thought it was an interesting thing for the Queen to say. It certainly caught Seven's attention." ()
 The episode was scripted as if it were a two-parter. The final draft script for the first of these parts was submitted on  (with further revisions up to and including 8 December of that year) and the final draft of the second part's teleplay was submitted on 2 December 1998 (being revised up to and including 15 December of the same year).
 Director Cliff Bole was instrumental in the decision to introduce the Borg Queen into the plot at the end of the first part. "I begged to get the Queen in the end [of that part]," Bole remembered. "Originally, they hadn't planned on it, and I said, 'Guys, you can't do this. You've got to tease, and you've got to bring these folks back, and you've got to have the Queen in this episode. You've just got to have what I call the end-teaser and introduce the Queen. I don't care if it's one page or two shots; just do it." ()
 The photon torpedo that destroys the Borg probe in the episode's teaser was initially deleted from the script for budgetary reasons. It was reinserted not long before the episode's creation came to an end. (Cinefantastique, Vol. 31, No. 11, p. 33)
 The script for this episode's first half defines the Borg Queen that appears here as being separate from the one in Star Trek: First Contact, as the scripted version of the queen's introduction in this episode specifies, "Although this Queen has a similar design to the one seen in 'First Contact', she is a different character with her own, distinct personality."
 The script also describes the intricate sequence wherein the Borg Queen's body is assembled by stating, "The Borg Queen descends in a free-floating alcove that lowers from a port on the ceiling. As the Queen comes closer, we can see her body integrate piece by piece in a startling optical effect. Legs, arms, neck, head, torso – all clicking into place." Visual effects supervisor Mitch Suskin noted, of the same scene, that the writers "wanted it to be impressive." (Cinefantastique, Vol. 31, No. 11, p. 33) Visual effects producer Dan Curry concurred, "[Brannon Braga] said that the Borg Queen will be reassembled, but let's do something 'new and cool'." ()
 The script for the episode's second half refers to the Hansens, while they are examining a drone aboard the Raven, as "like biologists tagging a 'wolf' in the wild," which is consistent with the fact that Brannon Braga and Joe Menosky often thought that the Borg were like wolves.
 Similarly, Erin Hansen's statement that she and her husband imagine the Borg Queen is "like the Queen of an insect colony" is in keeping with the fact that the Borg were initially conceived as a race of insects.
 The script for the installment's second part comments that the Borg assimilation chamber where Seven of Nine sees alien victims of assimilation was to be "a redress of the transwarp chamber seen in Part One."

Cast and characters 
 Brannon Braga felt that this episode was an important one for the character of Kathryn Janeway. "I think [it] was as important a show for Captain Janeway as it was for Seven," Braga mused. "I think Janeway became more heroic and more Human herself […] The scene with Naomi made [Janeway] a little warmer, a little more human. I think her relationship with Seven changed in that show, inexorably in some ways. They will always be in conflict, that's the nature of their mentor-pupil relationship. But I think they became a little more Picard and Data than they ever had been in 'Dark Frontier'." (Cinefantastique, Vol. 31, No. 11, p. 34)
 The fact that this episode's casting process took place in November and December 1998 hampered the search for suitable actors. Cliff Bole remembered, "Casting was a bit of a problem; the town [of Hollywood] was awful busy then. You know, winding down before Christmas everybody's trying to get shows done, and finding the right talent was very tough." ()
 There were early rumors that Alice Krige would return to portray the Borg Queen in this episode. (Cinefantastique, Vol. 31, No. 11, p. 33) However, Krige was unavailable, at the time. Even by , actress Susanna Thompson was still unsure of the reasoning for Krige's absence. Thompson, on that date, commented, "I wonder why Alice [wasn't] available! And I have no idea. There's all sorts of many different types of stories [but] she just wasn't available." (VOY Season 5 DVD, "The Borg Queen Speaks")
 Susanna Thompson, who had unsuccessfully auditioned to play the Borg Queen in Star Trek: First Contact, was asked back to audition for the queen in this episode. She recalled, "I used [Alice Krige's performance in First Contact] as a springboard for what I brought into the audition, and they cast me." (VOY Season 5 DVD, "The Borg Queen Speaks")
 Even though Susanna Thompson had appeared in several previous Star Trek productions (portraying  in ,  in  and Lenara Kahn in ), this was the actress' first encounter with large scale prosthetics. ()
 Susanna Thompson was aware that she was playing a different queen from the one in Star Trek: First Contact. Shortly after appearing in this installment, the actress commented, "I'm not the same Borg Queen. She's the new Queen of the hive. There are similarities, but we are different." (Cinefantastique, Vol. 31, No. 11, p. 32)
 Even after Susanna Thompson was cast as the Borg Queen, however, she still tried to take inspiration for her role here from Alice Krige's performance in First Contact. "I wasn't afraid of duplicating her," stated Thompson. "There was no time to imitate her, but there had to be similar elements because whatever Queen is clicked into the Collective, they all come from the same mind […] I was very much encouraged to make the Queen my own [though]." () Thompson also remarked, "I took some information from [First Contact]. They did not want me to duplicate Alice's character, but my own development of the background for this character was that there had to be elements that were the same, because ultimately they come from the same brain; they are an extension of the same central brain. There might be more knowledge at any given moment, but there is still the same background." ()
 The presence of a new Borg Queen was a notable departure from continuity for director Terry Windell. "I think you have a consistency in the characterization of the Borg, the collective mind, and how they operate," he stated. "Our Queen was obviously a different character; although she's still the Borg Queen, there's a very different take on it. So that's the part that I consider open territory to be different. The actual individual Borgs, I think, are manipulated very much in the same way, and that's how you keep the consistency and the continuity." ()
 Susanna Thompson felt that her primary task was to help make realistic the Borg Queen's effort to convince Seven of Nine to rejoin the Collective. "I think that my main role is to get to a point where the seduction becomes believable," noted the actress. ()
 Both Susanna Thompson and Terry Windell believed that, in this installment, the Borg Queen is a particularly maternal figure. "It's as if [the Borg Queen] comes back into [Seven's] life much like a biological mother would come back into some child's life, after years of not being there, and try and win her back, but in a very intelligent and manipulative way," said Windell. "Both these people are obviously incredibly intelligent and hold a lot of information. They're going to know what the other person is thinking, so they really have to work to push the buttons." () Thompson offered, "In an odd way, the Queen is a kind of maternal figure and of course, so is Janeway." () The actress clarified, "There really are two maternal figures. Janeway and the Borg Queen, in whatever twisted maternal way she is, are these two sides that are pulling at Seven and they represent her identity. She used to be here, she went away, and now she's come back to the Borg, and there is a sense of deprogramming and re-brainwashing. That's what the Queen does to her, and that's where the seduction lies." ()
 Susanna Thompson loved the effect of lights in the Borg Queen's lair following the queen as she moved, believing that the effect lent a greater sense of ambiance and power to her character. Thompson also felt that her Borg Queen's costume, particularly the restrictiveness of the outfit, aided her performance by making it hard to make any "extravagant" gestures. ()
 Susanna Thompson gained some useful advice from Brannon Braga. "Brannon told me to remember that every movement the Queen makes has a purpose," said the actress. () She elaborated, "Brannon was very helpful in that he wanted that kind of fluid movement that Alice had. When I got on set I pretty much got it, but he came down, watched me, and just said one thing – that there's no extraneous movement. I just realized that I might have been twitching a little bit and, because everything is perfect, any little twitch can stand out like a big one. That was real helpful. He also encouraged the quality of being… it's really not conversational… but there is not that drone quality about the Queen's speech." ()
 Susanna Thompson was additionally advised by Seven of Nine actress Jeri Ryan. "We talked about character, absolutely," recalled Thompson. () She also stated, "Jeri said for her, playing a Borg is constantly reinventing yourself in the moment." ()
 Jeri Ryan also helped Susanna Thompson bear the Borg Queen makeup. "Some of the most important information Jeri wanted to give me was about how to lie down!" exclaimed Thompson. "I had to lie vertical, but Jeri knew that, and she had a neck pillow. What I did was, I had a mound of robes on the floor on my trailer, neck pillows on top of them, and then I was able to lie somewhat comfortably." ()
 The collaboration between Susanna Thompson and Jeri Ryan was enjoyable for the latter actress. "Susanna Thompson, who is a friend of mine, was fun to work with," Ryan said. "As the Borg Queen, she did a beautiful job." (Cinefantastique, Vol. 31, No. 11, p. 28)
 Jeri Ryan was extremely enthusiastic about "Dark Frontier" in general. "That could have been a feature," she opined. "I was very impressed with the way that whole show came together, not just the script, but the production values all around were outstanding […] I loved seeing exactly what made [Seven of Nine's] parents tick and what made them end up the way they did, and exactly how they had gotten there in the first place. It very much had the flavor of Dian Fossey, the woman who studied and lived with gorillas, to it; following the Borg in the wild. I thought it was very well done and very well thought out." (Cinefantastique, Vol. 31, No. 11, p. 28)
 Although the Hansen family had been shown twice before, they had to be recast for this installment. "I think the original actress who played Seven's mother was unavailable and working in New York," remarked Cliff Bole, "and we just had to go searching […] Seven's parents were cast late." ()
 Both Terry Windell and executive producer Rick Berman were fond of Susanna Thompson's work on this episode. (; ) Windell opined, "She was very good." () Cliff Bole was likewise pleased with the results of the casting process, such as with finding Katelin Petersen to play the young Annika Hansen. "We lucked out," he said, "but, by God, we looked; it got really tight." ()

Props, makeup, wardrobe, and sets 
 Susanna Thompson found the makeup and clothing involved in this episode's production to be highly elaborate. "It was all that Star Trek can be," she observed, "this great, big, theater side of it, with costumes and makeup." (Cinefantastique, Vol. 31, No. 11, p. 33)
 According to the unauthorized reference book  (p. 291), the clothing used for Species 10026 consisted of stock costumes, including Romulan civilian clothing from  and .
 Susanna Thompson wore the same costume as Alice Krige had worn for Star Trek: First Contact, but with some subtle alterations. Thompson noted, "They adjusted it for me. Our body types were similar, but it wasn't quite made to fit my body." (Cinefantastique, Vol. 31, No. 11, p. 32) Similarly, the Borg Queen makeup for both productions was handled by the same person, Scott Wheeler, of whom Jeri Ryan enthused, "[He] did a phenomenal job on her makeup." (Cinefantastique, Vol. 31, No. 11, p. 28) There were a few changes to the makeup, however; for example, the mechanical structure that this episode's Borg Queen wears on the back of her head was slightly different from that which Krige wore, with some new lights, and the contact lenses (which were specially silverized at a space center in Texas) were the exact same kind of lens, although custom-made for Thompson. Some alterations were made on the set of this installment. "There were adjustments to the makeup in the center of the face and the eyes, the lips of course, and the forehead," remembered Thompson. "They didn't want me to look as wet as Alice, so they had to make sure that looked okay." ()
 It was due to lengthy durations that Susanna Thompson had to wear the Borg Queen costume for, coupled with the fact that the costume wasn't completely fitted to match Thompson's physical proportions, that the actress found the costume uncomfortable. Firstly, it took five and a half hours for her Borg Queen makeup and costume to be put on. Shortly after working on the episode, Thompson described the costume as "like a very, very tight wetsuit" of which the long days had made her tired. (Cinefantastique, Vol. 31, No. 11, p. 32) She also complained, "I found the costume, probably because it fit Alice better than it fit me, slightly constricting, particularly around the shoulders […] It was not an easy experience, physically." Conversely, makeup supervisor Michael Westmore took note of the fact that Thompson "was able to tolerate the contact lenses a little easier" than Alice Krige had. ()
 Susanna Thompson found her physical transformation into the Borg Queen to be a memorable experience. She declared, "It's so bizarre to have makeup spray painted on you; it's a very bizarre feeling. I felt like I was in the shop!" ()
 Terry Windell was sensitive to Susanna Thompson's predicament. "It was incredibly taxing for Susanna, but she was a real trouper," Windell remarked. "She's into six hours of makeup before I even see her on the set and then there's also the costume. She's wearing metallic contacts which, once you get fatigued – and we're using smoke on the set – can really be an irritant. So she really had to work hard, and it's hard work to look effortless […] It was very gruelling for her." ()
 Other production staffers were on hand to help Susanna Thompson with the costume. "I had to have two costume people work with me," the actress remembered, "just to get the costume in place and ready to shoot." (Cinefantastique, Vol. 31, No. 11, p. 33) She also stated, "There was always a costume maker with me to help me get out of the costume right away if I needed to go to the bathroom, and, being someone who doesn't really like to have a person constantly around me, that was a hardship." () Thompson additionally stated that "always having to count on somebody else to help you through things" added to her tiredness. (Cinefantastique, Vol. 31, No. 11, p. 33)
 Susanna Thompson theorized that an element of her costume had a practical application; "I have an electrical unit on the back of my head, and I guess you're left with the notion that that's what controls the light [in the Borg Queen's lair] really." ()
 Due to the fact that the writers were working on the episode's teleplay throughout the pre-production stage, some of the sets had to be designed without full knowledge of the script. Cliff Bole stated, "Our set designer, Richard James, had to pretty much put a set together without knowing the ending, and he had to build the Queen's set without knowing how the second part was going." ()
 Richard James tried to give the set for the Borg Queen's lair an unusual design. "I wanted something different from what we've seen before, so I made the Queen's lair look as if it was a sphere," commented James. "The whole set was about two stories tall and was made with all new drawings. The inside of her lair is curved to give it a spherical feel. I wasn't necessarily trying to follow the shapes used in First Contact; it just kind of came out that way, and I really like the look. The normal Borg walls are so square and flat that I wanted to add some depth and something real interesting. I also cut out the cylinders and made wafers instead, kind of like a large watch battery." Terry Windell opined that, although similar Borg corridors to the ones here had been shown in Star Trek before, the newness of the set for the Borg Queen's lair gave the production crew "some freedom." ()
 The lighting in the set for the Borg Queen's lair impressed both Cliff Bole and Terry Windell, Bole noting that it was a lot more extravagant than normal. "I know that [on 'Dark Frontier'] we went for an incredible lighting package. Theatrical lighting, almost a rock-and-roll package for a lot of the work." ()
 The idea of having some of the set's lighting concentrate on the Borg Queen was thought up by Terry Windell. "I requested that we have a very different look than we had seen before, and we had these computerized lights installed in the set that they could program to move," Windell explained. "Since the Borg Queen deals with controlling the whole collective by her mind, we thought it would be interesting that, as she moved around, some of the lights actually followed her." ()
 Jeri Ryan was impressed with the sets of this outing, remarking, "The sets were amazing." (Cinefantastique, Vol. 31, No. 11, p. 28)
 The sphere that Kim saw crawling around (and thinks it's an auto-generation unit, of some kind) is the same prop used in  by Riga as 'measuring instruments' as he is boarding the Delta Flyer.

Production 
 Similar to how this episode was scripted in two parts, the installment was also filmed as two separate segments, with Cliff Bole directing the first half and Terry Windell helming the second part. Due to the pressures regarding the amount of alloted time provided for the episode's production, Bole was gratified that there were two directors. Whereas Bole was a Star Trek veteran who was well acquainted with working on productions that involved the Borg (he having directed the  two-parter  and ), relative newcomer Terry Windell had to do some research. The latter director admitted, "Obviously, I referred to First Contact and the episode where they pick up Seven. I researched about four or five episodes that were strong in Borg. The feature and 'The Gift' were probably the strongest in terms of how to handle the material." ()
 Brannon Braga was of the opinion that this episode was "very difficult to produce." (Cinefantastique, Vol. 31, No. 11, p. 34)
 In common with the writing of the script and the casting process, the episode's production took place in November and December 1998. In fact, when Cliff Bole started filming his part of the episode, neither the script nor the guest cast were ready yet. "A lot of times when they were looking [for actors], I was shooting, so that added to it," Bole stated. "We were putting [the guest cast] together pretty much at the fifth hour, and I had to depend on the boys upstairs to do some casting without me, because my plate was full […] We started shooting before we had actually had a completed script […] The phone was ringing all the time; that's how Brannon and I had to work, because he was working so hard on the second part and finishing the first one. I mean he answered the phone immediately and we hammered our way through it." ()
 Cliff Bole was attracted to the possibility of utilizing a steadicam for this outing. "I used the steadicam quite a bit and the town was so damned busy, it was tough to line up the guys I like and the cameramen I like," Bole reflected. "[The steadicam] became my main tool by the nature of the design of the set. It became more of a tool than a creative piece, because it just handled all the problems that came out of the design." ()
 The reason that the Hansens were cast late was, as Cliff Bole explained, "because that part of the show we did towards the end [of the production schedule], because we weren't sure how much we were going to do on it." ()
 The casting of the Borg Queen also had a correlation on the production process. Cliff Bole recounted, "They hadn't quite got the Queen yet, she wasn't available; so I had to come back to shoot. I had to come back after I'd finished filming, about a week later, to shoot my part with the Queen, which was just the ending [of the first part of the show]." ()
 Cliff Bole and Terry Windell worked together in an attempt to ensure that the transition between their scenes was seamless. Windell remembered, "I actually went on the set and watched what Cliff was doing so that we would have continuity. The biggest aspect was he didn't introduce the Queen's lair until the last act of his show and the majority of my show takes place there, so that was the big sequence we had to collaborate on, and we actually were there on the same day when he was filming his sequence." ()
 This is the final Star Trek episode that Cliff Bole worked on as a director.
 As Borg corridors had repeatedly been shown on Star Trek, Terry Windell intended to make the ones here seem a little atypical by giving them a cramped look, such as in the shots where an appalled Seven passes victims destined for assimilation, and various Borg drones. "I tried to lens it a bit differently than I've seen before: I tried to use longer lenses and compress a lot of the space, just to get a sense of claustrophobia," Windell related. "What I've seen before a lot in the Borg corridors is wide lenses to give that kind of distorted perspective and, you know, get a little disjointed, and it tends to make the set look really open and big. Once the Borg Queen orders Seven to go back in and actually participate in assimilating another race, we felt that it should be in Seven's mind's eye, what the corridor was all about. I felt it should be very claustrophobic." ()
 Working the lighting effect that was characteristic of the Borg Queen into the production caused Terry Windell some scheduling problems. "What we would do is rehearse and when we had the blocking down with Susanna, then we would program the lights accordingly and she was fantastic about hitting her marks […] In terms of difficulty, what that did, the actual time to program the lights is something you don't really see when you're blocking out a week's worth of work." () Nevertheless, Windell was still proud of the work of those responsible, including himself, for creating the dramatic atmospheres in the Borg sets. "I think that what we did in the Borg corridors and the Queen's lair was […] featuresque, the drama and the lighting, so that it's not always about seeing everything in total clarity; it's about using light and smoke." ()
 Susanna Thompson's long days of enduring her makeup and costume generally consisted of around 21 hours. (Cinefantastique, Vol. 31, No. 11, p. 32) She reflected, "My days were very long. I had no idea; they were 20, 21 hour days. One day I think I did 22 hours." Terry Windell offered, "By the time I'm at the end of a normal day, she's almost into 20 hours." ()

Visual effects 
 Terry Windell remarked on the usefulness of the episode's visual effects; "I think that the visual effects give it the production value. When they describe the multitude of Borg vessels you have to see that." ()
 The CGI for both parts of the episode was done by Foundation Imaging, involving the input of Foundation's visual effects supervisors Robert Bonchune and Adam "Mojo" Lebowitz as well as director of animation John Teska. (Cinefantastique, Vol. 31, No. 11, p. 32) Bonchune handled the visual effects of the episode's first half, whereas Mojo dealt with the VFX of the second part. () The episode also incorporated contributions from Foundation Imaging staffers Koji Kuramura (who was responsible for most of the Borg Unicomplex's construction, based on a maquette created by Dan Curry, and for the revamping of the damaged Borg sphere), David R. Morton (who created numerous Astrometrics graphics), Dan Ritchie (who both built and blew up the Borg probe), and Brandon MacDougall (who built and designed the Borg Queen's ship). () Dan Curry was also involved in modeling the queen's ship. (Cinefantastique, Vol. 31, No. 11, p. 33)
 Star Trek: First Contact provided a precedent on which the visual effects artists based the episode's variety of new Borg ship designs, as well as the look of the Unicomplex. "We had the feature, to some degree, to refer back to, to make sure that this appears to be in the same universe," noted Mitch Suskin, who acted as the visual effects supervisor for the first half of the episode. (Cinefantastique, Vol. 31, No. 11, p. 33)
 A visual effect whose creation was particularly hurried was the interior view of the Borg probe's destruction. Mitch Suskin remembered, "As they cut the show, they looked at it and said, 'We really want more action, more drama.' We found out about that as they were finishing second unit photography." With the visual effects team having had little notice that the effect would be wanted, Art Codron (the visual effects coordinator for the episode's first half) subsequently ran across to the set and obtained the necessary background plates. Suskin described the effect's creation as "a true team effort" that involved a Borg drone CGI model from Foundation Imaging. He continued, "John Teska gave us a couple of variations of [the single] Borg flying backwards, with interactive light passes. Then we took it into the bay, dug through our vast library of explosions, and pieced it together in an afternoon, between his animation, the elements we had, and a little bit of Harry [animation] work here and there to stitch it all together. It's the one shot in the film when you see an explosion ripping through and the Borg getting blown backwards." (Cinefantastique, Vol. 31, No. 11, p. 33)
 Mitch Suskin noted that some of the effects for the episode's first half were harder to create than others; "The big challenges in that show, as far as I am concerned, were the Borg city, the Unicomplex, and the scene where [the Borg Queen's body is assembled]." (Cinefantastique, Vol. 31, No. 11, p. 32) Suskin also believed that the writers were not alone in wanting the queen's construction to look impressive, a similar sequence having been created for Star Trek: First Contact. "We all secretly wanted it to be at least as good as what was done on the feature," recalled Suskin. "We wanted to be a little bit different." (Cinefantastique, Vol. 31, No. 11, p. 32)
 By examining the set for the Borg Queen's lair, Dan Curry came up with the idea of having the queen's lower body enter from below, via floor panels, and then robotically assemble. Curry then mapped out the sequence with storyboards that, despite being quite detailed, also left ample room for the other team members to be creative. () Live action footage of Susanna Thompson's head, made-up to match that of the Borg Queen, was shot for the sequence. () Mitch Suskin reflected, "We shot a plate of the actress, […] a closeup that they tracked in. She's just standing on the stage in front of a bluescreen, but we actually had the camera tilting, and coming down, so we'd have a little bit of a perspective change. It was tracked in and composited at Foundation Imaging." (Cinefantastique, Vol. 31, No. 11, p. 33) Indeed, most of the sequence was done with CGI by John Teska. (Cinefantastique, Vol. 31, No. 11, p. 32; , et al.) This was because the queen's unique alcove did not actually work as an elevator. (Cinefantastique, Vol. 31, No. 11, p. 32)
 Not only was the bluescreen footage of Susanna Thompson used for close-ups of the Borg Queen's head, but the sequence also involved CG models of the queen's head and body as well as the apparatus that physically assembles her. () Rob Bonchune recalled of John Teska's work on the sequence, "He built all the piping. I mean, basically, there was nothing in there. There was a thing in the background where she came down live, but he meshed the live actress to CG stuff […] and he built all the piping when it comes up through the floor. All we had was this plate, and he actually put the images on CG stuff and blended it in, and you see holes on the floor." () Teska also lit the apparatus. A shot wherein the combination of CG and live action elements was used to represent different parts of the Borg Queen is the one where the upper and lower portions of her body are fastened together by small hooks that latch into her. "[That] was just a production shot of her," said Suskin. "Everything that latches in was done at Foundation." (Cinefantastique, Vol. 31, No. 11, p. 33) Following this shot, the episode concludes solely with live action footage. The effect itself incorporated only six cuts and hardly any work for Susanna Thompson. ()
 When Rob Bonchune saw the first test of the assembly machinery rising out of the floor, he was pleasantly surprised by how real John Teska had managed to make the effect seem. (; Cinefantastique, Vol. 31, No. 11, p. 33) The sequence was so effective that it fooled people into thinking it had been done entirely on set. "Mitch [Suskin] told me," recounted Bonchune, "that when they were viewing the tape over at Paramount, people would walk in to look at it and say, 'Oh, you guys shot that practical?' That's good […] It's pretty impressive." ()
 As transwarp travel had previously been shown (visualized with the same effect) in both  and , the visual effects artists initially intended to make another reuse of the same effect in this installment. "We pulled out that reference," Mitch Suskin stated, "because we assumed since it was the same term, that we would use that again. Peter Lauritson and the other producers looked at it and wanted something flashier. The thing that they actually liked was from [the fourth season finale] , the slipstream. What we did was basically take the slipstream effect and change the color a little bit." (Cinefantastique, Vol. 31, No. 11, p. 33)
 The Raven was also revived for this episode, a previous version of the starship having been featured in a fourth season episode of the same name as the craft. "It was really a matter of almost starting over from scratch," explained John Teska. A basic framework of the craft was in Foundation Imaging's possession, of which they did a render that they sent to Star Trek: Voyager Senior Illustrator Rick Sternbach. (Cinefantastique, Vol. 31, No. 11, p. 33) He remembered, "I got a printout of the ship from Foundation, so I would have a three-quarter perspective […] We cut it down from eight or nine decks to four decks tops. This changed the scale of the windows and the entry hatches, and that sort of thing." () Foundation Imaging then built the craft from Sternbach's refinements. (Cinefantastique, Vol. 31, No. 11, p. 33)
 The transporter effect used in the flashback scenes corresponds with the effect used in  and .
 The wide shot of the Delta Flyer being retrofitted with the transwarp coil was a re-use of the matte shot from . The shot of the Delta Flyer exiting Voyagers shuttlebay was another example of reused footage, having been used in both "Extreme Risk" and . Both shots were scripted to be stock optical shots.
 All the visual effects were transfered between the first and second halves of the episode, as Ronald B. Moore took over the supervising of the VFX. He commented, "We did all of the Queen interiors, and a lot of the ships, exploding the Queen's ship and going through the Borg city, the unicomplex. Foundation did some great work. I think the quality of the images we got was really terrific." (Cinefantastique, Vol. 31, No. 11, p. 33)
 Much of the visual effects footage of the climactic battle involving the Delta Flyer and Borg Queen's vessel inside a transwarp conduit was added late by Rick Berman. Ron Moore remarked, "At the end when Berman was making the final cut, he put some of those [shots] back, the interior of the warp conduit, the firing, and the chasing, which I thought was fabulous. Just before finalizing the cut, he felt that we needed the shots, so we put them back in, in a rush, because at that point we are usually talking about having another two weeks to work." Moore also expressed gratitude that the visual effects team were able to pull together the effect, despite the rush. (Cinefantastique, Vol. 31, No. 11, pp. 33 & 34)
 Jeri Ryan was thrilled with this episode's optical shots, stating, "The effects were amazing." (Cinefantastique, Vol. 31, No. 11, p. 28)

Music 
 When the Hansens first detect a Borg cube, the music is reminiscent of the V'ger-themed music from . (, p. 289)

Continuity and trivia 
 This is the final Star Trek episode directed by Cliff Bole.
 Terry Windell noted a comparison between this episode and "The Gift", saying the reason he found that reviewing that installment helped with the production of this one was "especially since ['The Gift'] dealt with Seven's transition from Borg to being more human, and this whole story is about the possibility of her becoming Borg again." ()
 Susanna Thompson believed that the Borg Queen's attempt to persuade Seven of Nine to rejoin the Borg Collective here is similar to the relationship between Data and the queen in Star Trek: First Contact, describing both relationships as a "seduction" but also referring to each as a different form of that. (; )
 The episode's teleplays date the flashback sequences in the first part of the installment as "twenty years" before the rest of the events in that part and the flashbacks in the second half as "a full year" later.
 This episode marks the first and only appearance of the Borg probe in a Star Trek series. However, the probe's rectangular design was resurrected for this episode; a Borg "tetragon" (imagined as being much larger than the one shown here) was temporarily considered to appear in Star Trek: First Contact, as a possible replacement for the Borg cube in that film. (Delta Quadrant, p. 289, et al.) This episode also marks the first and only appearance of the diamond-shaped Borg Queen's ship.
 Janeway claims that use of the transwarp coil has brought Voyager fifteen years closer to home, over a distance of 20,000 light years. This implies an average speed of around 250 million miles per second. Voyagers speed capabilities have previously been noted in  ("4 billion miles per second" at Warp 9.9),  ("2 billion kilometres per second"), as well as implied in  (222 million miles per second) and  (170 million miles per second).
 Seven of Voyagers photon torpedoes are seen to be used in this episode (one of which was transported before detonation), two having previously been used in . This brings the total number of torpedoes confirmed to have been used by Voyager over the course of the series to 49, a total which exceeds the irreplaceable complement of 38 that had been established by Chakotay in the first-season episode .
 Voyager loses a shuttlecraft in this episode, for a total of ten, after having previously lost nine shuttles in , , , , , , , and . In this episode, the shuttle is sacrificed as part of a strategic distraction.
 At the opening of this episode, the Borg voiceover announces the detection of 143 life forms aboard Voyager, yet the crew complement had previously been established as 152 just two episodes earlier in . This apparent discrepency is not accounted for.
 Paper makes a rare appearance in this episode, in the form of several drawings stuck to the walls of USS Raven. Paper previously made an appearance in .
 It is revealed in this episode that a single Borg regeneration alcove requires 30 megawatts of power.
 Seven is seen in her purple-tone jumpsuit for the first time. This outfit was introduced because the previous blue one had been difficult to film against bluescreen backdrops. ()
 This Borg Queen reveals herself to be from Species 125.
 In this episode, it is revealed that the Borg designation for Humans is Species 5618.
 The transwarp conduit represents the eleventh time besides the series premiere (after , , , , , , , , , and ) that the Voyager crew is presented with the possibility of returning home much faster than by conventional warp travel. In this case, the technology works, if only for a short while, and provides a significant shortcut.

Previous episodes 
 This episode makes several references to the events of , and the eponymous ship of that episode also makes several appearances, in flashbacks that serve as a prequel to that episode. No dates are given for , but this episode establishes that the events of that episode happened "over a year" earlier.
 Janeway states that the crew of Voyager have "proven ourselves against the Borg once before, twice before", in a reference to the events of the duology  and , and the episode . Janeway also points out to Seven that it's been "over two years since you came face to face with the Collective", in another reference to . 
 Chakotay misquotes Seven as saying, two years previously, "I will betray you". She actually says "we will betray you" (using the Borg penchant for the first-person plural tense) in .
 While discussing the records of Seven's parents, Neelix claims that the only thing he has of his family is a picture of his sister. This picture made an appearance in the earlier fifth-season episode .

Other Star Trek series 
 The Hansen logs indicate that Federation knowledge of the Borg existed prior to the events of , citing the limited information as "rumor and sensor echoes." No doubt the El-Aurians must have been a source of at least some of the knowledge, since the  witnessed their escape in . It is somewhat puzzling, however, that the Starfleet crew of the  are unaware of the Borg and the Hansens in the earlier TNG episode. As Joe Menosky remembered, the writers of this episode were well aware of the discontinuity when they devised this installment. "There was no way in the world we were going to get rid of the Hansen arc, just because it didn't match exactly what had happened when Q first threw the Enterprise near that Borg cube […] There should be some mention in a database somewhere, and Picard should have known. There was a little bit of that knowledge […] In our minds, the Borg were a very slender rumor, and the Hansens followed up on the rumor and just disappeared. Whether that completely holds water or not, that's all the justification we needed to go with the Hansen arc. Even if we couldn't have come up with that justification, we would have done it anyway. I think you are denying new audiences the chance to see this arc that couldn't be told if you were going to be faithful to something that was established a decade ago. We are not willing to be that rigid with continuity." (Cinefantastique, Vol. 31, No. 11, p. 34)
 Paris claims that Ferengi attempted to break into Fort Knox "about ten years ago". This would have been just a year after humanity made official first contact with the Ferengi in 2364, in .
 When Seven first encounters the Borg Queen face to face the Queen says: "Welcome Home" followed by a scene cut. This echoes the end of  when the female changeling says the same thing to Odo and there is also a scene cut.
 The Borg in the flashbacks appear as they did in Star Trek: First Contact instead of the dry pasty look of the Borg during Star Trek: The Next Generation.
 The Queen tells Seven she is the first drone that has regained its individuality, apparently denying the existence of Hugh and the rest of Lore's rogue Borg faction, as well as disregarding Captain Jean-Luc Picard's temporary assimilation into Locutus.

Reception 
 Brannon Braga was ultimately thrilled with this episode, saying, "It turned out to be really, really amazing." () Braga selected some of his favorite moments from the episode. "The best scene of the picture, I thought, was when the Queen was finally pushing [Seven] to the edge, pulling out all the stops, and finally just about to get her to crack, and Janeway's voice comes in. That was the best moment in the show, definitely. The scenes between Seven and the Queen I really liked […] Seeing Janeway in the little scene with Naomi, that was another one of my favorite scenes. Seeing people come to the Captain somehow felt right in that show." Braga also remarked that he thought the transition of Janeway and Seven becoming more like Picard and Data was "a step in the right direction." He was proud, too, of the episode's production and was of the opinion that the installment succeeded in measuring up to Star Trek: First Contact. "The team really rose to the occasion, and it turned out great," Braga enthused. "It had more action than First Contact. On a television budget, the fact that we in some ways imagistically took First Contact a step further is an impressive achievement, and I'm just really proud of that. We all enjoyed it very much." (Cinefantastique, Vol. 31, No. 11, p. 34)
 Joe Menosky especially liked the scenes showing Seven of Nine's temporary reintegration into the Borg Collective. "The thing I liked the most about the episode," Menosky critiqued, "shows how cool a character Seven of Nine is. I love the scenes where she's in her Seven of Nine catsuit, and there she is walking around Borg corridors as if she is at home. I think there is great power to that image, and it perfectly captures her character as being this Human child raised by wolves […] I love the image when Janeway takes off, because she has no choice, from that Borg sphere and Seven is there amongst the Borg. I think it's a really powerful image, and goes to the heart of her character." (Cinefantastique, Vol. 31, No. 11, p. 34)
 Rick Berman was also happy with the installment, saying he was "extremely proud" of it. Berman additionally enthused, "Having the Borg Queen in [the] mix fits beautifully in the story […] [The episode] brings a very sensual and spooky element to the relationship between Seven of Nine and the Borg. All of our expectations were exceeded in bringing it to the screen." ()
 This episode originally aired as a feature-length episode but it was later broken up into two parts for reruns in syndication. According to the unofficial book Delta Quadrant (p. 290), this episode – when shown on UPN – was the first of many Voyager episodes that the network edited by two minutes so as to include an extra commercial in each advertising break, thereby increasing revenue. As of 2020, this edited version of the episode, missing the scene in which Janeway chastises Torres’ dismissive attitude towards Seven, is still shown by several streaming outlets.
 The episode achieved a Nielsen rating of 4.73 million homes, with a 7% share. It was the most watched installment of Star Trek: Voyager (on first airing) since . (Cinefantastique, Vol. 31, No. 11, p. 34; )
 In Great Britain, Sky first showed the episode as two separate parts that aired on the same night as each other. After the first part was shown, the continuity announcer joked that the second part would be postponed because the tape had broken. (Delta Quadrant, p. 290)
 Unusually for the BBC (which frequently aired Star Trek two-parters as feature-length editions), this episode was broadcast as the two-part version on 11 and .
 This episode won an Emmy Award for Outstanding Special Visual Effects for a Series. Star Trek nearly swept the category that year; also nominated for it were  and .
 The book Star Trek 101 (p. 175), by Terry J. Erdmann and Paula M. Block, lists this episode as one of the "Ten Essential Episodes" from Star Trek: Voyager.
 Manny Coto cited "Dark Frontier" among his favorite Star Trek productions. The episode inspired him to feature several multi-episode-arcs in the fourth season of .

Apocrypha 
 Both the Borg probe and the Borg Queen's vessel, introduced here, are featured in the non-canon PC games Star Trek: Armada and Star Trek: Armada II, wherein the probe is known as a Borg "Interceptor". In Star Trek Online, the probe is a frigate-level ship.

Video and DVD releases 
 UK VHS release (two-episode tapes, CIC Video): Volume 5.8, catalog number VHR 4798, 
The episode was released in feature-length format, and the video featured a reversible sleeve: one side with the standard Voyager design, the other a special "Feature Length TV Movie" design, "featuring the return of the Borg Queen".
 In feature-length form, as part of the UK VHS collection Star Trek: Voyager - Movies: Volume 4 (with "Unimatrix Zero"), release date unknown
 As part of the VOY Season 5 DVD collection
 As part of the Star Trek: Fan Collective - Borg collection

Links and references

Guest stars 
 Susanna Thompson as Borg Queen
 Kirk Baily as Magnus Hansen
 Laura Stepp as Erin Hansen
 Scarlett Pomers as Naomi Wildman

Co-stars 
 Katelin Petersen as Annika
 Eric Cadora as Alien
 Majel Barrett as Computer Voice

Uncredited co-stars 
 Patrick Barnitt as
 Borg drone
 Holographic Borg drone
 Trish Baylord as Species 10026 member
 Debbie David as Russell
 Lin Chong as Voyager sciences ensign
 Carl D'Amico as Species 10026 member
 Tarik Ergin as Ayala
 Chiara Harris as Species 10026 member
 Kerry Hoyt as Borg drone
 Guy Korte as Species 10026 member
 Joyce Lasley as Lydia Anderson
 Mark Major as Borg drone
 Tom Morga as
 Borg drone
 Holographic Borg drone
 Sam Mountain as Species 10026 member
 Louis Ortiz as
 Borg drone
 Borg Queen's drone
 Erin Price as Renlay Sharr
 Dominic Rambaran as Species 10026 member
 Keith Rayve as
 Borg drone
 Borg Queen's drone
 Craig Reed as Species 10026 member
 Lynn Speier as Species 10026 member
 Jean Vera-Montes as Species 10026 member
 Catherine Yurkovich as Species 10026 member
 Unknown performers as
 ""
 ""
 "Needle Fingers"
 Three of Five
 Four holographic Borg drones
 Human hologram
 Two Borg drones

Stand-ins 
 Brita Nowak – stand-in for Jeri Ryan and Laura Stepp
 Stuart Wong – stand-in for Garrett Wang

References 
22nd century; 2350; Alixia; anger; assault; assimilation; assimilation chamber; asteroid field; automaton; auto-regeneration unit; away team; bad habit; beer; bio-dampener; bioelectric interference; biogenic charge; biokinetic analysis; biomolecular scanner; boarding party; Borg; Borg Collective; Borg cube (unnamed); Borg Queen's ship; Borg drone; Borg probe; Borg scout ship/Borg sphere (unnamed); camouflage; career; Class 2 shuttlecraft; class 5 probe; coffee; collective mind; combadge; command interface; compression phaser rifle; course; cranial capacity; critical velocity; cubic kilometer; cybernetic; damage; data node; database; debris; ; Delta Quadrant; density; ; dilithium; dinosaur; dispersal field; dozen; drone manifest; duty shift; Earth; emergency power; emotion; encryption code; environmental systems; evasive maneuvers; exobiologist; exo-plating; exploration vessel; fear; Federation; Federation Council on Exobiology; Ferengi; Ferengi burglars; field magnitude; field notes, USS Raven; field regulator; force field; Fort Knox;  fuel; gold; Grid 325; Grid 532; heading; heart; heist; hive mind; holodeck; holo-image; hull; Human; individuality; interplexing beacon; ; ion storm; insect colony; interplexing beacon; intruder alert; isogrid; kiloton; knowledge; Ktarian; Ktarian beer; laser scalpel; light year; log entry; logistics; Maquis; medical repair drone; megawatt; meter; metric ton; micro-suture; money; motion sickness; muffin; multi-adaptive shielding; museum; nanoprobe; nanoprobe virus; narrow beam transporter; neural transceiver; New World Economy; newcomer; nightmare; ocular implant; offline; Operation Fort Knox; orbit; Papa; pattern enhancer; personal log; phaser pulse; photon torpedo; physiology; physiometric conditions; pint; plasma conduit; polytrinic alloy; power matrix; power distribution node; power node; power utilization curve; propulsion system; ; ; red alert; regeneration cycle; regenerative ability; replicator; rescue mission (aka rescue operation); ; Romulan Neutral Zone; sarcasm; scout ship; second; sector; sense of humor; sensor range; servo-armature; shield generator; shield matrix; shield modulator; shield generator; shower; sickbay; spatial charge; Species 125; Species 5618; Species 6961; Species 10026; Species 10026 homeworld; Species 10026 vessel; Starfleet; "steady as she goes"; strategy; subdermal probe; subspace energy fluctuation; subspace particle storm; suffocation; surgery; tactical drone; tactical simulation; teracochrane; teradyne; teraquad; threat; throne; time index; toast; toy; tractor pulse; transpectral analysis; transport coordinates; transporter beam; transporter frequency; transporter range; Transporter Room 1 and 2; transwarp; transwarp chamber; transwarp coil; transwarp conduit; transwarp signature; trial run; triaxilation; triquantum wave; tritanium; unicomplex; Unimatrix 01; Unimatrix 424; United States dollar; vanity; vessel; viral sequencer; warp profile; warp signature;

External links 
 
 
 
 

de:Das ungewisse Dunkel, Teil I
es:Dark Frontier
fr:Dark Frontier, Part I (épisode)
nl:Dark Frontier
VOY episodes