Regeneration (episode)
A scientific team in the Arctic discovers a crashed derelict ship and two cybernetic alien bodies from over a hundred years earlier. When the aliens revive themselves, they kidnap the scientists, hijack their vessel and move out into space where Enterprise must confront them.

Summary

Teaser 

The Arctic, Earth. A scientific expedition is in progress. A transport flies in a research team. Three Human scientists - ,  and Moninger tramp through the snow, holding scanners. They find what they seek: the crash site of an alien craft.

They break up, searching in different directions. Rooney picks her way quickly but carefully through debris and snow, until her scanner starts beeping. She stops, kneels and brushes away snow, uncovering something. She calls her comrades over to see what she has found.

As they join her, they discover the face of a frozen humanoid figure, unlike anything they have ever seen. Its skin is grave-pale, mottled with black. A grotesque cybernetic implant is where its left eye should be.

Act One 
The scientists comment on the creature's humanoid appearance and how well preserved it is. Drake, the leader, calls in for a base camp to be set up. Rooney gets another reading, goes to its origin and finds another frozen cyborg.

Later, with the camp set up, the two lifeforms have been placed on tables in a laboratory. They are covered, neck down, in metallic exo-plating. Moninger examines them, while Rooney examines a small piece of the ship's hull.

They show Drake their findings. Moninger, after examining a bulky cybernetic prosthesis that one of the lifeforms had on its right arm where the forearm should have been, has found that it had been integrated into the creature's circulatory and nervous system; it could have probably controlled the device as if it were its own flesh and blood. He has also examined the eyepiece of the first discovered individual and has found that with it, the creature could have seen most of the EM spectrum. Rooney finds that their ship crashed about a hundred years prior. Drake instructs them to transmit the findings to Starfleet.

They hear a mechanical whirring and see the tool at the end of the cybernetic prosthesis whirring and clicking. After a hundred years, frozen in ice and snow, it still works. A further examination of the prosthesis is in order.

Moninger does the examination, looking at a bit of the tissue from the part of the prosthesis that was attached to the lifeform's arm under a microscope. He shows Drake. Microscopic machines, some form of nanotechnology, are among the s, repairing them. There are thousands of them in each creature. Not only are they regenerating the tissue, but they are repairing the mechanical parts on a microscopic level. The prosthesis is fully functional, with Moninger calling it "as good as new."

As incredible as he finds this, Moninger also finds it disquieting. How far will this regenerative process go? These creatures do not look very friendly. What if they are fully revived and prove dangerous? And just what were they doing on Earth a hundred years ago? Did they come in peace or otherwise? He suggests that, just to be on the safe side, they freeze them again and examine them under more controlled conditions. But Drake says no; re-freezing might damage them. They will remain in the laboratory and the regeneration will be allowed to continue. He goes outside to where Rooney is further investigating the ship's debris.

Her report to him is that, from the fact that every piece of outer hull debris has precisely the same curvature, the ship appears to have been a perfect sphere, about six hundred meters in diameter.

Meanwhile, another researcher brings a flask of a hot beverage for Moninger in the lab. He advises Moringer that he's been asked to step away to conduct repairs elsewhere at the base camp, he looks at the two lifeforms and voices concern; will Moninger be alright? Moninger assures him that he will, showing him a rifle he has for protection. Alone again, Moninger pours a cup of coffee as he hears a mechanical clicking noise from one of the lifeforms. Alarmed, he checks the monitor that displays the lifeform's neural activity. Nothing.

Outside, Drake and Rooney have found something else: a transwarp coil. But though they can guess as to its function, i.e. faster-than-light space travel, the technology is way beyond them.

Inside the lab, Moninger continues to watch the monitor. Suddenly, a spike appears. Then more spikes, then full signals; neural activity has begun in the lifeform's brain. The lifeform awakens with a gasping breath. Moninger grabs a scanner and begins scanning it, as it opens its organic eye. Its mouth closes and its face lapses into a cold stare, as it beholds him. 

Outside, Drake and Rooney hear his scream and the firing of his weapon.

They rush back to the lab, which is now ruined, with two large streaks burnt through the walls from the rifle and all the equipment thrown to the floor. They find one lifeform on the table where they left it, while the other is gone. They find Moninger behind some tossed-over shelving, gasping painfully. The left side of his face is streaked with black, mottled lines that are spreading, as the nanoprobes that the revived lifeform injected him with move visibly under his skin, multiplying rapidly and transforming him. Drake tells Rooney to get a medical kit. As she turns to do so, she turns right into the revived lifeform, its organic eye regarding her coldly, the red laser light of its eyepiece on her face.

Three days later, at Starfleet Headquarters, Commander  rushes into the office of Admiral Maxwell Forrest. He informs the Admiral about the prolonged loss of contact with the research team. Forrest orders him to ready a . He and an armed team go to the site. All they find is snowed-in, abandoned shells of structures; no sign of the research team, their transport or the debris from the crashed ship.

Act Two 
Out in space, aboard , Captain Jonathan Archer speaks to his senior staff in the situation room. Admiral Forrest has informed him of what has happened and has sent him the data the scientists gathered, believing the creatures abducted the research team. The transport the team used was detected leaving Earth at warp 3.9.

This shocks Commander Tucker as these transports cannot exceed warp 1.4. Archer surmises that the aliens improved the ship's systems using technology from the wreck of their own vessel. Lieutenant Reed wonders what Starfleet expects Enterprise to do since they are a longways away from the Arctic. Archer informs them the transport's projected course puts it within six light years of the current position of Enterprise. Forrest has ordered that they intercept it and rescue the research team.

Sub-Commander T'Pol surmises that isolating the transport's warp signature should not be difficult. Archer orders a tactical alert and orders Ensign Travis Mayweather to lay in the necessary course.

As the ship heads for the area, Reed, speaks to Doctor Phlox about the aliens' possible weapons. He and Phlox look at the research team's biometric data on the creatures but find no evidence of weapons. This worries Reed; the research team was well armed; how did these two aliens manage to overpower them without weapons?

As Enterprise continues toward the coordinates, Captain Archer is in his ready room, reading something on his computer terminal as T'Pol calls him to the bridge; they are receiving an automated distress call from a Tarkalean freighter. On the bridge, Ensign Sato at the communications station tells him what the message says: the freighter is under attack. Archer orders Mayweather to alter course toward it.

Upon arrival, Enterprise observes the freighter is heavily damaged and dead in space. The transport has also been altered, far from the ordinary-looking vessel it originally was, as it cuts into the freighter with a cutting beam. Archer orders a hail to the transport, warning to cease and desist immediately or be fired on. The transport responds with a volley of proton bursts at Enterprise. T'Pol scans nine Human life signs on the transport but the readings are erratic. Reed believes he can disable its weapons; Archer orders it done. Enterprise fires on the transport, which breaks off its attack and takes off at warp. Archer orders a  deployed to the freighter to bring the survivors aboard.

The two survivors, a male and a female, are lying unconscious in sickbay. Their faces and hands are marred with emerging implants, similar to the aliens. Dr. Phlox informs Archer and T'Pol that the two should live, but then shows them what is happening to them - the alien nanoprobes in their bodies are transforming them into a cybernetic hybrid. T'Pol surmises this as the reason for the erratic Human life sign readings; the research team is likely being similarly transformed.

Archer asks if the nanoprobes can be removed. Phlox says no; they are multiplying extremely fast - he could never remove them all. T'Pol advises that the two Tarkaleans should be secured in the decon chamber, but Dr. Phlox says that he cannot treat them properly there and he does not believe them to be a danger to the crew. Archer, however, is not so sure and advised he will have Lieutenant Reed post a guard in sickbay.

In Archer's ready room, T'Pol arrives to inform him she has contacted Tarkalea and informed them of their rescue of their people. Archer shows her what he was reading before. It is a  that was given at Princeton University 89 years prior by the inventor of Human warp drive, Zefram Cochrane. In it, he had spoken about what really happened during the events surrounding his first warp flight and first contact with the Vulcans, that a group of cybernetic creatures from the future had traveled back in time to "enslave the Human race" and they tried to prevent the flight but were stopped by a group of Humans, also from the future.

A skeptical T'Pol reminds Archer of Cochrane's over-active imagination and the fact that he was frequently intoxicated. Archer acknowledges this, saying that nobody took the story seriously and Cochrane recanted his story a few years later, but there are similarities between the story and the aliens that cannot be ignored. And if the story was indeed true, then these creatures may be heading back to where they came from, so that another attempt can be made.

In sickbay, the two Tarkaleans begin to stir. Dr. Phlox goes to the male, who wakes up very agitated. He demands to know who Dr. Phlox is and where he is and is horrified to see the implants in his hands. Dr. Phlox tries to calm him down and grabs a sedative to administer to him, as the Tarkalean suddenly convulses and screams with pain.

As Dr. Phlox begins to inject the sedative, the implants take full control of their victims. On the other biobed, the female rises behind the security guard. The male grips Dr. Phlox's arms with incredible strength and the woman throws the guard across the room. The male forms a fist and brings it to Dr. Phlox's neck. Metallic tubules dart out, injecting Dr. Phlox with nanoprobes, who collapses in a heap, unconscious.

The two Tarkaleans leave the room via a maintenance shaft ladder. Meanwhile, the skin around the injection point on Dr. Phlox's neck starts to change color, as the nanoprobes begin the process of transforming him.

Act Three 
While unconscious, Phlox begins hearing the collective voices of the aliens before being revived by Captain Archer, Lieutenant Reed along with a team of security officers, all well-armed. Dr. Phlox quickly scans his neck and confirms what has happened; he has been infected with the nanoprobes. Scans by the security officers reveal the route the two Tarkaleans used to leave. Archer orders Reed to seal off the maintenance shaft, to post guards at every access point and find and subdue them. Phlox warns Reed about their greatly enhanced strength and to avoid being touched by them. He then scans the  who was with him when the attack happened and confirms that he hasn't been infected. Archer orders the officer to keep guarding sickbay.

In engineering, Commander Tucker shows Captain Archer scans of the modified transport. It has been greatly enhanced with more ful engines, hull plating, weapons and other modifications Tucker cannot even guess the functions of. Archer notices that the aft plating has not yet been enhanced; a couple of spatial torpedoes should break through and knock out a nearby EPS manifold, disabling the ship.

T'Pol calls from the bridge; she has detected the transport, less than two light years away, moving at warp 4.8; a significant development; its top speed has doubled in less than twelve hours. Archer orders Ensign Mayweather to alter course to intercept it.

Meanwhile, in the maintenance shaft, Reed and his security officers move carefully, looking for the Tarkaleans, using scanners to track them down. They find Starfleet computer terminals that are now filled with strange alien readouts.

They come upon the individual that used to be the Tarkalean woman altering more panel circuitry, changing it to the same alien design by plunging the same tubules used to attack Dr. Phlox into the circuitry. As she does, the circuits instantly morph into modified alien technology, taking on a black and green color. Reed sternly and repeatedly orders her to stop, but she ignores him. They fire their weapons at her, but the stun setting has little effect and subsequent blasts hit nothing but personal shields. They set their weapons on maximum and fire again but fail to pierce the shields.

The female Tarkalean turns and advances on them. Remembering Dr. Phlox's warning, they quickly withdraw, only to run into the cybernetic lifeform that used to be the male Tarkalean. It overpowers one of them and tries to inject him with nanoprobes. With its tubules shooting out mere inches from the guard's head, Reed smashes the officer's fallen phase rifle into the Tarkalean's head, temporarily stunning it. He calls the bridge and reports the location of the two to Captain Archer and that they appeared to have been modifying systems. Archer asks T'Pol what is in that area. Her answer: warp plasma regulators, essential for the warp drive to function.

Suddenly, Mayweather reports the destabilization of the ship's warp field. Archer recalls that there is an outer hatch in that area. He orders Reed and his officers to clear the area and orders Ensign Mayweather to bring Enterprise out of warp. As Enterprise drops to impulse, the captain orders T'Pol to open the hatch. The two Tarkaleans are instantly blown out into space. Archer regrets having to kill the two Tarkaleans, but T'Pol tells him he had no choice. The captain orders course for the transport resumed and orders Reed to work with Tucker to find out exactly what the two were doing to the systems.

In sickbay, Ensign Sato, who is wearing a phase-pistol at Lieutenant Reed's insistence, brings food for Dr. Phlox and his small menagerie of alien animals. He accepts her offer to feed the animals, but he will not eat himself, for fear of accelerating his metabolism and causing the nanoprobes in his system to spread even faster. He now has a sickly white and black-mottled patch over the tubule wounds. She desires to stay and keep him company once she finishes but he insists that, for her own safety, she leave immediately when done. "I underestimated these nanoprobes once; I do not intend to make the same mistake twice," he tells her.

Meanwhile, Tucker and Reed examine the modified circuitry, but they cannot determine what has been done to it. Captain Archer goes to the mess hall, where he finds T'Pol. She advises him that perhaps it is better not to try to rescue the Humans, saying that it is logical to assume that all aboard the transport has either been transformed or are transforming and that bringing any of them aboard may be extremely dangerous. The transport should be destroyed, she adds, but Archer is not willing to make that choice just yet, as Dr. Phlox summons him to sickbay.

His condition has worsened - his hands tremble, the patch on his neck has spread over the entire right side of his face, a second patch has formed on his forehead and a third is forming on his right hand. The doctor tells Archer that his Denobulan immune system seems to be baffling the nanoprobes, but they are persistent and will adapt and keep multiplying. Eventually, he will be transformed. However, he has found a possible treatment. Their processors appear to be susceptible to omicron particles. Exposure to this may destroy them and cure him, but the level has to be very high, lest even one nanoprobe survive. Such a high level would be very painful.

Should it fail, he has one surefire cure: death. He gives Archer a hypospray containing a neural toxin that will almost instantly end his synaptic functions and asks him to use it if the treatment fails. Archer wonders if Phlox isn't jumping the gun, but Phlox is resolute: he will not allow himself to be turned into one of the cybernetic creatures.

In the armory, Reed and one of his security officers test modifications of the phase-pistols to try to get them to penetrate the alien shields. Upon finding a particular setting that works, they begin modifying as many weapons as they can before Enterprise catches up with the transport in less than an hour.

Upon reaching the transport, Enterprise finds that its defenses have been further enhanced since their last meeting. It accelerates almost to the limit of Enterprises warp 5. Archer orders speed increased to match. The ship begins to shudder with the effort, but they close the distance. Archer orders Reed to target the EPS manifold that he and Tucker agreed on.

The transport drops out of warp. Ensign Sato reports an incoming transmission from the transport; it is an activation sequence. On Archer's order, she tries to stop it, but cannot. The alien-modified circuits suddenly become active. Main power and other systems, including weapons, begin to fail. Archer angrily realizes the truth: the Tarkaleans sabotaged the circuits, modifying the appropriate systems so that this signal would cause them to fail. Sato reports a hail coming in. Archer orders it answered. He angrily begins to identify himself and Enterprise, but he is cut off by words spoken in a cold, soulless, multi-track resonant intonation: 

"You will be assimilated. Resistance is futile."

Act Four 
The transport hammers Enterprise with weapons fire, wearing down her defensive polarized hull plating. Commander Tucker feverishly works trying to undo the sabotage so that they can at least regain use of weapons, but it will take several minutes. Captain Archer gets an idea and orders Reed to come with him to the still-functioning transporter, telling T'Pol to be ready to beam them off the transport.

Meanwhile, in sickbay, Phlox' condition has worsened considerably. Both sides of his face now look cybernetically enhanced, as well as both hands. He again hears voices in his mind, his movements are hunched and painful and his voice is tremulous, but he determinedly sets up the omicron treatment, telling the guard to activate it once he is in the imaging chamber. He gets in and the guard activates it as Phlox grimaces in agony.

Captain Archer and Lieutenant Reed, armed with Reed's modified phase-pistols, plan to take out the EPS manifold with an explosive charge themselves and beam onto the transport where they find its interior has been completely modified with the alien technology.

Suddenly, two aliens round a corner and advance on them. They open fire and incapacitate them. As Archer scans one of their bodies, he realizes that he labors in vain to rescue them, or anyone else on the transport - these two are no longer Human; the one he scans used to be Rooney.

Meanwhile, things get much worse on Enterprise as six aliens board the ship. T'Pol dispatches security to try to stop them, but the officers soon experience the same result as Reed and his team did against the Tarkaleans: their shots neutralize two then hit nothing but force fields on the remaining intruders when their shields adapt. The aliens advance relentlessly, pushing the Enterprise officers ever backward. Meanwhile, Commander Tucker manages to isolate one of the alien power relays and begins to reroute  to the engines and weapons.

On the transport, Archer and Reed continue toward the conduit, disabling the lifeforms that try to stop them with phase pistol fire. Reed is surprised by an alien attacker, who lifts him against a wall by the neck, only for Archer to disable it by ripping out the wiring on its head. They find the conduit and Reed quickly places charges on it while Archer fends off advancing aliens.

At the same time, Enterprises polarized hull plating finally fails, and the transport begins to use its cutting beam on her hull. Archer and Reed plant the explosive charge on the manifold as the aliens' shields adapt to their weapons. Archer has T'Pol beam him and Reed back. Once aboard, he has Reed detonate the explosives. The desired effect is achieved - the transport's power is disrupted. At the same time, the aliens beam back to the transport as Trip manages to disable the alien circuitry on Enterprise, restoring power to the systems. Returning to the bridge, Archer is asked about the research team by T'Pol - he grimly informs her there is no longer anyone aboard they can help.

Reed suddenly reports with alarm that the transport's systems are being restored; it is charging weapons. Archer, now versed in what they are dealing with, knows exactly what to do; he orders all weapons fired at the transport's warp core. Enterprise opens fire with all her arsenal at the transport, which explodes as she quickly departs. 

With Enterprise having resumed its original course, Archer and T'Pol find that Dr. Phlox has fully recovered; the omicron treatment was successful. However, Dr. Phlox has ominous news; he tells them about the strange experience he had while he was infected; the voices in his mind, as if he were part of a group consciousness. T'Pol suggests he hallucinated it, but he does not think so; he got the distinct impression the aliens were trying to send a subspace message: a numerical sequence he heard over and over again. He gives them a PADD with the numbers.

In the ready room, Archer informs T'Pol that he had the computer analyze the numbers. The results have him even grimmer than before. They are the spatial coordinates of Earth - the aliens sent a message detailing Earth's location. T'Pol asks him where the message was sent to. His answer: deep inside the Delta Quadrant. T'Pol tells him that there is no immediate worry as a subspace message would take at least two hundred years to get there, providing it even makes it at all.

This does not comfort Archer. He surmises that the invasion has merely been postponed… until the 24th century.

Log entry 
 Captain's starlog, Enterprise NX-01, 2153

Memorable quotes 
"There's no reason to assume they're hostile.""They don't exactly look friendly."
 - Drake and Moninger, discussing the frozen aliens

"You seem a little jumpy."
"Cybernetic corpses, digging through frozen remains in the middle of the night. Why would I be jumpy?"
 - Drake startles Rooney

"Buried in the ice for a century."
"Hard to believe anything could survive."
"Handsome devil."
 - Tucker and Archer viewing images of the Borg taken in the Arctic

"What sort of people would replace perfectly good body parts with cybernetic implants?"
"You, of all people, should be open-minded about technology."
"Well, I don't have a problem with it… so long as it stays outside of my skin."
 - Reed and Phlox

"Use extreme caution, Lieutenant, their physical strength has been enhanced. It is critical that you do not let them touch you."
 - Phlox, having been injected with nanoprobes

"…, you will be assimilated. Resistance is futile."
 - The aliens

"I doubt there's any immediate danger. It would take at least 200 years for a subspace message to reach the Delta Quadrant, assuming it's received at all."
"Sounds to me like we've only postponed the invasion, until what… the 24th century?"
 - T'Pol and Archer

Background information

Production history 
 Filmed:  – 
 Second unit filming: 
 Premiere airdate:

Production 

 The first outline for the episode, dated 5 January 2003 and written by Mike Sussman and Phyllis Strong, was titled "Untitled Borg on Ice."   
 When the assimilated transport attacks the Tarkalean freighter, and later Enterprise, it is seen cutting a circular chunk into their hulls. This was an allusion to the TNG episode , when the Borg take a cylindrical cross-section of the . The writers had initially hoped to show the cylinder being tractored away from the Tarkalean freighter, but this effect was deemed too expensive. ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
 Because of David Livingston's often quick directing style, the filmed episode was several minutes too short. Several scenes had to be written in including the scene with Reed and Phlox in the armory talking about the weapons of the Borg, the phase-pistol efficiency test scene with Reed and Alex in the armory, and the scene in the base camp with Rooney scanning the debris of the sphere. ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
 However, when confronted with the script some production (fan) staffers were initially less than enamored, or as Production Illustrator John Eaves has put it, he being called upon to design Arctic One and its subsequent "Borgification", "During Season 2 of Enterprise we got wind of a future script #49 called "Regeneration". Everyone in the art dept.… started to read the little teaser and we all gasped in Horror at about the same time, THE BORG!!! NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO!!!!!!!!!. We all were not feeling to happy about this new TNG alien showing up in an episode of Enterprise before Kirk… well this will throw all lines of trek history out the window. A few days later the first script arrived and reluctantly we all went to our desks and read away… Hey this is OK I thought It does work and it ties into Trek history as defined in "First Contact". As you recall The Borg sphere went back in time to destroy the Phoenix warp ship thus changing earth's history and killing the threat of Humanity in the future. The Sphere gets fired upon by the Enterprise-E and the evil plot is eliminated… Now we are working on Enterprise and this new story picks up on the debris from the sphere being discovered in Antarctica. like "the Thing" once thawed out the Borg go back to doing what they do best! Assimilation! My job on this one was to create an Arctic exploration vessel that makes the discovery and later becomes Borgified. The first sketch is high profile vessel that I thought when Borged could form a cube. This idea was passed on and the second sketch got the approval. The ship is lightly based on a stylized snow mobile. Once Borged it goes thru a variety of changes and this second sketch try’s to convey on of the stages of coverage. Pierre over at Eden modeled this one." 
 Arctic One as it appeared in the beginning and Borgified was illustrated by John Eaves and rendered in CGI by Pierre Drolet. 
 The ENT Season 2 Blu-ray features the special "Outtakes" in which two scenes from "Regeneration" can be seen from a behind the scenes view. The first scene includes the talk between Archer and Tucker in engineering and the second scene includes some goofing around in sickbay with Scott Bakula, Dominic Keating, John Billingsley, and Paul Scott.
 The second season Blu-ray release also features seven production stills from "Regeneration" in the special "Photo Gallery". These shots include David Livingston on set, approaching Borg drones in a corridor, the three Arctic scientists, Reed climbing up the ladder, and stills of Vaughn Armstrong, Brian Avery, and Mark Major.

Sets 

 The simulated snow for the Arctic Circle set was previously used as salt for the Rura Penthe set in the second season episode . ()
 Among the debris in the Arctic Circle is a filming model of the 's front saucer section, originally created for the crash sequence in . ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
 The maintenance shaft sets were later re-used as corridor sets of the  in the episodes  and  and of the Romulan drone ship in , , and . ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
 A power distribution node from inside the assimilated Arctic One was later sold off on the It's A Wrap! sale and auction on eBay.

Props and costumes 
 The arctic gear suits seen in this episode were designed by Robert Blackman. ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
 Bonita Friedricy's arctic archaeology team coat was later sold off on the It's A Wrap! sale and auction on eBay.  Her Borg costume was sold off at the 40 Years of Star Trek: The Collection auction at Christie's. 
 The arctic gear outfits of Chris Wynne, Adam Harrington, John Short, and Vaughn Armstrong were also sold off on eBay.     The boots worn by Armstrong featured a brand tag from North Face. In addition, an arctic gear undershirt, worn by Jim Fitzpatrick and also by John Billingsley, Connor Trinneer, and Vince Deadrick, Jr., was also sold off. 
 The costumes of the two Tarkaleans, played by stunt actors Mark Chadwick and Nicole Randall, were sold off on eBay. Their costumes featured several attached Borg skin pieces and Borg implants.    
 Two pairs of the prop charges seen at the end of the episode were sold off on the It's A Wrap! sale and auction on eBay. They were later re-used as stun grenades by the MACO in the third and fourth season.  
 The medical scanner of the Arctic Team was a re-use of ' Temporal Observatory device from  and was also sold off. 
 Other props from "Regeneration" which were auctioned include the prop Borg arm,  an Earth Science Institute communicator,  and a medical report PADD. 
 The remote control used by Reed at the end was previously used by Trip Tucker in the episode .

Cast and characters 

 Bonita Friedericy, who played  in this episode, is the wife of Phlox actor John Billingsley.
 In an audio commentary for "Regeneration" on the ENT Season 2 Blu-ray, Friedericy and Billingsley joked that Friedericy got the part of Rooney by sleeping with Tucker actor Connor Trinneer. In reality, Friedericy auditioned for the role of Rooney, but when she walked into the room to audition, Star Trek: Enterprise creators and Executive Producers Rick Berman and Brannon Braga pretended not to know her. "It was very unnerving, because I'm very shy and I didn't know whether I should say hello or not," Friedericy explained. "So, I sort of waved at them and they both kind of looked distastefully at me, and looked up at the ceiling and then they said, 'Go,' and I thought I wasn't gonna get it, and it was sad, but then I got the call and I got it."
 On the set, Friedericy was referred to as a baby Borg. "I was called the baby Borg because Borg are never little, and I'm five-foot-three," she remarked. Applying the Borg makeup to Friedericy for Rooney's assimilated appearance took five-and-a-half hours. This was longer than usual because the makeup team, not having done any Borg for a while, initially made a mistake with Rooney's Borg makeup. To portray the assimilated Rooney, Friedericy also wore a Borg costume that Roxann Dawson had previously worn, in . Once Friedericy was made to look Borg, it was time for her to go before the cameras as the assimilated Rooney. 
 For budgetary reasons, the producers had chosen not to hire a stunt performer for Rooney's death scene, as this would have necessitated not only the hiring of a stunt woman, but the creation of another (expensive) Borg costume. Director David Livingston had imagined a violent death for Friedericy's character, who was to be shot by phase-pistols before falling backwards out of frame. There was concern that the actress might not be able to safely perform the stunt, but after speaking with the actress and consulting with the episode's stunt team, it was decided that Friedericy would perform the stunt herself. "I was really pleased with myself," she reminisced, "because they squibbed me [repeatedly], and I did my own stunt." Each time Friedericy performed her stunt, John Billingsley applauded from off-camera. ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
 Writer Mike Sussman expressed the remarkable likeness of Phlox actor John Billingsley and his stunt double Vince Deadrick, Jr. who not only was the Stunt Coordinator on Enterprise but also the regular stunt double of Jonathan Archer actor Scott Bakula. ("Regeneration" audio commentary, ENT Season 2 Blu-ray)

 Background actor Louis Ortiz played one of the two Arctic Borg drones. He also played several Borg drones in the prequel, Star Trek: First Contact, and appeared numerous times as a Borg in . On set he was known for teaching actors how to move like an alien and behave like a specific species. ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
 This episode marks stunt actor Paul Scott's first Trek appearance. He will make two more in the third and fourth season, though uncredited.

Continuity 
 This episode is a sequel to the events of . ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
 The Bynar species, which first appeared in the  Season 1 episode , are mentioned in this episode by Phlox as being an example of an admirable use of cybernetic technology.
 The oft-mentioned Tarkaleans, first named in the  episode , make their first and only on-screen appearance in this episode.
 The invasion that Archer predicts does indeed happen in the 24th century, in 2366, 213 years after the events in "Regeneration", in .
 This episode contains the only mention of the Delta Quadrant in the entire run of Star Trek: Enterprise.
 This episode shares a similarity with  in that the antagonists remain unnamed, though they are a well-established species within the Trek universe. ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
 Reed's line about shooting the Borg drones with holographic bullets was an in-joke by the episode writers. In the holodeck scene in Star Trek: First Contact, drones could indeed be killed by holographic bullets, assuming the holodeck safety protocols were turned off. ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
 Archer's method of physically disabling one of the Borg, by tearing some of its wires out, is reminiscent of the way Captain Picard disabled a Borg in .

 This episode includes the only appearances of the Borg in Enterprise. Similarly, the  pilot episode, , was the only appearance of the Borg in that series, although the  was among the defense fleet against the Borg during the Battle of Sector 001 in Star Trek: First Contact.
 For the sequence outside of Starfleet Headquarters, a recurring moving matte painting was chosen. This shot was filmed way back during the first season and also appeared in the episodes , , , and .
 The episode introduces a potential predestination paradox into the overall Borg story arc. At the end of the episode, Archer reveals that the Borg on the assimilated transport transmitted a series of "spatial coordinates" to the Delta Quadrant, pinpointing the exact location of Earth. T'Pol theorized it would take at least two hundred years for the message to reach the Delta Quadrant, implying that if the coordinates were received, they could explain why the Borg sent a cube to the vicinity of Federation space approximately two centuries later, as seen in the TNG episode, . That cube destroyed several Romulan and Federation outposts in 2364. A series of encounters with the Federation followed over the next several years, culminating in the Battle of Sector 001. During that battle, a Borg sphere travelled to the 21st century in an effort to assimilate Humanity in the past, as seen in Star Trek: First Contact. The sphere was subsequently destroyed by the time-traveling Enterprise-E in 2063, and debris from the sphere, including several drones, fell to Earth and was frozen in the Arctic. 90 years later, the thawed-out drones assimilated the Arctic researchers who had discovered them, and after fleeing in the researchers' ship, the drones transmitted Earth's coordinates to the Delta Quadrant, starting the causality loop over again.
 The ending of the episode is notably similar to that of the  episode , in which the crew of the  fight and destroy a hostile alien species, though not before said species managed to transmit a signal giving the location of Earth, and raising the fear that more of the aliens could invade again someday. Interestingly, the parasitic beings featured in that episode were originally intended to be agents of what would become the Borg, though no on-screen connection was ever suggested, due to it being dropped in light of budget constraints and the 1988 Writer's Strike.
 Although Cochrane never personally encountered the Borg in First Contact, this episode establishes that he knew quite a bit about them and even claimed to have come "face to face" with them in the commencement address Archer reads on his monitor. It seems likely that his colleague Lily Sloane filled him in after her experiences with the Borg aboard the Enterprise-E and Cochrane embellished the story a bit when he talked about it years later.

Music 
 The episode has a much darker theme than other installments of Enterprise, reinforced by the music score composed by Brian Tyler. This is Tyler's second and last contribution to the second season, the first being .
 The soundtrack "Star Trek: Enterprise Collection", released in , featured five pieces from "Regeneration" on disc four – fan favorites: 
 Borg Crash Site/Borg Awakening (3:13)
 Archer Tells Plan/Distress Call/Phlox Attacked (3:10)
 Hive Mind/Borg Hunt/Dead in the Water (6:43)
 Borg Attack/Borg Attack 2 (7:23)
 Message in a Bottle/Postponed (0:58)

Reception 
 "Regeneration" proved to be one of the most popular episodes of Enterprise. Wired wrote that it was "a fun way to merge the franchise's past with its future," and included it on a list of twelve "all-time best Star Trek episodes."
 Ain't It Cool News reviewer James Michael Kozak, aka "Hercules Strong," gave the episode three-and-a-half out of five stars, saying, "Audiences may find themselves caught up in a genuine sense of dread and alarm," adding that, "performances are strong all around, but John Billingsley and Linda Park turn in some especially sharp work." 
 Jamahl Epsicokhan at Jammer's Reviews wrote that the episode had "a deviously clever premise," and that it, "contains more pure entertainment than most of this season's episodes of Enterprise." He added: "What's important, though, is that the episode works on both levels — as an hour of action in its own right as well as something that assembles these various franchise fragments." Epsicokhan awarded the episode three-and-a-half out of four stars, saying, "The simple fact is, this is one of Enterprise's most engaging action episodes to date."  
 Blogger Darren Mooney at The M0vie Blog.com writes that "Regeneration" is a "fantastically constructed action adventure, one that makes the Borg more threatening than they’ve been since First Contact." Mooney adds that the episode, "works almost perfectly. It is a late-season shot of adrenaline, and one that provides a sense of the energy and urgency that will come to define much of the third season." 
 The Digital Fix wrote that the installment was, "the best episode of the show’s first two years." Reviewer Baz Greenland added, "'Regeneration' succeeds on almost every level, telling a sequel to Star Trek: First Contact, tying into later continuity and most significantly, making the Borg genuinely scary again after Star Trek: Voyager neutered them." 
 Blogger J.P. Halt at his website Random Musings wrote, "writers Mike Sussman and Phyllis Strong have proved themselves to be the big finds of the second season. Many of the season's strongest episodes have had their names attached." He graded the episode a 9/10, saying it was "about as well-structured as a single-part episode of 'action Trek' could reasonably be expected to be." 
 There was some controversy among fans over the fact that the Borg drones omitted their standard greeting ("We are the Borg") when they hailed Enterprise, conveniently keeping Starfleet in the dark about the identity of the cybernetic species. In their podcast commentary, the writers pointed out that the Borg did not always use this greeting; in  the Borg did not say, "We are the Borg" when they first encountered the Enterprise-D, nor did they say it when they confronted Picard's ship again in . The writers added that the drones in "Regeneration" had been separated from the Borg hive mind; thus, they were not the Borg, but a small collective.
 According to Friedericy and Billingsley, some fans believed that the episode "violated the timeline," and that by introducing the Borg, the series was "jumping the shark."  ("Regeneration" audio commentaries, ENT Season 2 Blu-ray)
 Manny Coto cited this as one of two episodes, from the first two seasons of Star Trek: Enterprise, that he "especially enjoyed", the other such episode being . ()
 Artwork depicting a scene from "Regeneration" graced the the  calendar . The artwork for the month of January, titled "Things from Another World" by CG artist John Teska, featured an image of the crashed Borg sphere and the transport Arctic One.

Apocrypha 
 The events of this episode form the basis of the story for the  game Star Trek: Legacy. A Vulcan scientist named T'Uerell is assigned to study the Borg debris and after learning their true nature, injects herself with Borg nanoprobes. Armed with knowledge of future events, she spends the next two centuries building her forces and waiting for the opportunity to seize control of the Borg Collective in order to use them to bring a state of total logic to the Alpha Quadrant.

Media 
 As part of ENT Season 2 DVD
 As part of Star Trek: Fan Collective - Borg
 As part of ENT Season 2 Blu-ray
 Star Trek: Enterprise Collection (soundtrack)
 , 
 , 2003
 , 2003, set report by Penny Juday
 ,

Links and references

Guest Stars 
 Vaughn Armstrong as Maxwell Forrest
 Jim Fitzpatrick as

Co-Stars 
 John Short as 
 Bonita Friedericy as 
 Chris Wynne as Dr. Moninger
 Adam Harrington as Researcher
 Mark Chadwick as Male Tarkalean
 Paul Scott as

Uncredited Co-Stars 
 Adam Anello as Starfleet Headquarters crewman
 Brian Avery as Borg drone
 Jef Ayres as Haynem
 Craig Baxley, Jr. as operations division crewman
 Amy Kate Connolly as civilian
 Mark Correy as Alex
 Shawn Crowder as Borg drone
 Nikki Flux as command division crewman
 Peter Godoy as operations division crewman
 Glen Hambly as operations division ensign
 Peter Harmyk as Starfleet security officer
 Andy Keith as Borg drone
 Mark Major as Borg drone
 Eddie Mathews as operations division ensign
 Eric Norris as Borg drone
 Louis Ortiz as Borg drone
 Bobby Pappas as Starfleet Headquarters crewman
 Nicole Randall as Tarkalean female
 Pablo Soriano as Borg drone
 Warren Tabata as Starfleet security officer
 John Wan as operations division crewman
 Todd Wieland as operations division crewman
 Unknown performers
 Arctic researcher (voice)
 Female Starfleet admiral
 Three Borg drones
 Voice of the Borg
 Zefram Cochrane (image)

Stunt Doubles 
 Vince Deadrick, Jr. as
 Stunt double for Scott Bakula
 Stunt double for John Billingsley
 Marty Murray as stunt double for Dominic Keating

References 
2064; 2153; 24th century; 47; A-6 excavation team; acceleration; abduction; access point; activation sequence; admiral; aft plating; aircraft carrier; alien; alloy; alpha team; angel hair pasta; animal; antimatter residue; April; Arctic; Arctic Archaeology Team; Arctic Circle; arctic gear; Arctic One; ; arctic research team members; arm; armory; assimilation; assimilation tubule; assignment patch; automation; autonomic system; avionics control system; aye; backpack; base camp (Arctic base camp); base pair; bat; bed; Beta Magellan system; biobed; biology; biometric data; biosign; birth; boarding party; blood; body part; book; Borg; Borg alcove; Borg Queen's sphere; bottle; bridge; ; bullet; Bynar; Bynar surgeon; Bynar child; cage; captain; captain's starlog; carbon; cargo; ; cell membrane; cell rate; century; channel; charge; christmas tree; circuit; circulatory system; class; cloud; ; cocoa; coffee; cola; cold storage; command chair; command division; commander; commencement address; communicator; contamination protocol; coordinates; corridor; course; creature; crew; crewman; crewman third class; Cunningham; cup; cutting beam; cybernetic creature; database; day; death; debris; deck; decon chamber; Delta Quadrant; Denobulan; density; desk; deuterium; devil; diameter; distress call; DNA; doctor; door; dose; dozen; drawing; drink dispenser; earpiece; Earth; Earth Sciences Institute; eating; Edosian slug; EEG; electrode pad; EM spectrum; EM trace; energy shielding; engineer; engineering; ensign; ; ; ; ; ; EPS manifold; evacuation; excavation team; exo-plating; experiment; explosive; eye; eyepiece; fire extinguisher; First Contact; flag; flag officer uniform; flesh; food; force field; freighter; frigate; fuel useage; future; galley; genetic analysis; geometric; glacier; glove; Golden Gate Bridge; graduation ceremony; graduating class; group consciousness; guard; guava; hail; hand hold; hand scanner; hatch; heading; heart; heating unit; history; holographic; homeworld; hour; hull; hull plating; Human; Humanity; humanoid; hybrid; hypospray; ice; iced tea; image archive; imagination; imaging chamber; immune system; implant; impulse; infection; interference; intoxication; intramolecular processor; invasion; irradiation sequence; isolation; Jefferies tube; joke; junction; lab; ladder; lamp; lectern; Lepton diffraction scan; lettuce; lieutenant; lifeform; life support; light year; log; logic; long range sensor; loudspeaker; main power; maintenance shaft; ; mechanical component; medical kit; medical report; megajoule; mess hall; metabolism (cellular metabolism); meter; microscan; microscope; milk; minute; mission patch; model; monitor; Montana; name; nanoprobe; nanotechnology; nanotechnology database; NC; NC-05; neck; nervous system; neural toxin; neutron microscope; night; numerical sequence; NX class decks; office; omicron particle; operations division; orbit; organ; PADD; paper towel; paperwork; parietal lobe; particle; patient; percent; phase cannon; phase-pistol; Phoenix; photography; physical; physical strength; physician; physiology; pickaxe; plasma network; plasma rifle; polar bear; ; power cell; power relay; power system; power utilization curve; primary system; primary systems analysis; Princeton; prosthesis; proton burst; proximity scan; pulsar; pulsar frequency; pulsar triangulation; pulse; race; radiation; rank pip; ready room; recanting; regeneration; remote control; renal gland; researcher; research module; research team; respiration; retrovirus; room service; rootleaf; San Francisco; scanner; Science Council; sciences division; scientist; scope; scotch; second; secondary systems analysis; secondary systems log; security; security team; sedative; serving case; ship; shuttle; ; sickbay; sink; sir; situation room; ski; skin; slug; snow; snowplow; snowstorm; sol; space shuttle orbiter; spatial coordinate; spear; species; ; sphere; starboard; Starfleet; Starfleet database; Starfleet Headquarters; Starfleet Medical; ; starship; ; stun setting; sub-commander; subspace message; suicide; surgeon; synaptic function; synaptic processor; synthetic organ; table; tactical alert; Tarkalea; Tarkalean; Tarkalean freighter; tea; technology; telepathy; test; test flight; thermal damage; thermos; tissue; tomato; torch; torpedo; tracking station; transport; transporter; transporter alcove; transwarp coil; tray; trousers; turbolift; unnamed engineering tool; unnamed Humans; unnamed plants; unnamed Tarkaleans; vessel analysis; viewscreen; Vulcan; Vulcan sandworm; Vulcan scientist; warp; warp coil; warp core; warp drive; warp field; warp plasma regulator; warp ship; warp signature; water; weapon; weapons locker; weapons node; window; world; year; Zefram Cochrane's commencement address; zipper

External links 
 
 
 
 

cs:Regeneration
de:Regeneration (Episode)
es:Regeneration
fr:Regeneration (épisode)
it:Rigenerazione (episodio)
ja:ENT:覚醒する恐怖
nl:Regeneration
 ENT episodes