Through the Valley of Shadows (episode)
A fourth signal leads the USS Discovery to an insular world, where Pike is forced to make a life-changing choice. Burnham and Spock investigate a Section 31 ship gone rogue, leading to a discovery with catastrophic consequences.

Summary

Teaser 
While replaying one of her mother's mission logs, Michael Burnham receives a transmission from her foster mother, Amanda Grayson; Spock has told her about what happened on Essof IV. Burnham laments that all this time, she had thought her mother dead, when she had been in fact trying to stop Control from wiping out sentient life, and Burnham had stopped her; she felt as if she had failed her, then she lost her all over again. Amanda tells Burnham she has it backwards: She found her mother, and would be able to find her again. That moment, Spock enters, apologizing for the intrusion, but Captain Pike required them both. Amanda tells her children to take care of each other, and tells them she loves them. Spock tells Burnham another red burst has appeared.

In his ready room, Pike explains that the signal has been found over the Klingon planet of Boreth;  is shocked to hear this, but says only that it could not be Gabrielle Burnham, as the time crystal in the Red Angel suit was destroyed, and Saru adds that Gabrielle had claimed no knowledge of the signals. Spock speculates that it is likely another time traveling entity; Tyler wonders if it could be a trap, an agent of Control from the future, but Pike points out that none of the events from the other signals favor that theory, pointing out the Human settlers on Terralysium whose ancestors had been saved from 21st century Earth by the Red Angel. Burnham interjects, saying that speculation about the signals' meaning or their creator was unproductive, asserting that waiting for the signals to provide answers was a waste of time. She also points out that Leland is now Control, and they should be joining Agent  in the hunt to find him. Saru reminds Burnham that the 's archive would not allow itself to be deleted or removed, and that if Discovery joined the search for Leland/Control, they risked Control getting the entire archive. Pike understands Burnham's desire to "lead the charge" in hunting down Control, but safeguarding the archive was priority, which meant focusing on the task at hand: the signal over Boreth. Tyler explains that Boreth is revered by the Klingons because of the monastery on the surface dedicated to Kahless, the only non-native structure on the planet. He is uncertain why the signal has appeared there, but nonetheless would contact Chancellor L'Rell to arrange safe passage. Burnham watches him as he leaves, suspecting there is more than he is letting on.

Act One 
As Discovery enters orbit around Boreth, Burnham goes to Tyler in his quarters, demanding to know what he's not telling them. Tyler admits that Boreth is home to the son of Voq and L'Rell; he had wanted to raise the child, but instead it put both his and L'Rell's lives in jeopardy, so the boy was taken to Boreth to be raised as a "son of none", just as he had been. He apologizes, saying he couldn't tell anyone. Embracing him, Burnham expresses the wish that he had told her sooner, so he wouldn't have to carry it alone; he points out that it was something they both struggled with of late. At that moment, a secure communication comes in; a Section 31 ship missed its check-in. While Tyler says it could be nothing, Burnham believes when it comes to Leland/Control, "no inconsistency was too small". Tyler knows she wants to go after him for what happened to her mother, and admits he did not think it would be possible to stop her. At that moment, Saru calls over the intercom, telling Tyler that Chancellor L'Rell has arrived aboard a  . Before he leaves, he hands Burnham his Section 31 PADD, and tells her to be careful.

Coming aboard Discovery, L'Rell tells Pike and Tyler that the monastery on Boreth was the most sacred site in the Klingon Empire, and contact with outsiders has been non-existent "since our world was young". Pike emphasizes that Control was a threat to them all, and asks what could be there of value. L'Rell explains that the planet was home not only to the Followers of Kahless, but to a rare mineral native to the planet, and guarded by Klingon lives for generations: time crystals. The Red Angel suit was powered by a modified crystal, and Pike speculates that a crystal could allow them to send the Sphere data to the future after all. L'Rell considers the manipulation of time to be a weapon unlike any other, which is why the Empire no longer exploits the crystals. Pike believes their mutual survival depends on time manipulation to defeat Control, and perhaps finding the last three signals would allow them to do that. Tyler volunteers to beam down to Boreth, but L'Rell immediately objects, saying they would not have this conversation in Pike's presence. When Pike promises full discretion, seeing as time was of the essence, L'Rell admits that Tyler's presence on Boreth would endanger the life of their son. Tyler emphasizes he would not put the Empire at risk, but he had the right to see their son. "The dead have no rights," L'Rell replies; if both Tyler and the child were revealed to be alive after being publicly declared dead, it would leave the Empire vulnerable to sedition, and she forbids him to go. Tyler shouts in Klingonese that he was not hers to command. L'Rell replies in the same tongue that the rule was no contact for their son's safety, but Tyler retorts that the signals changed the rules; L'Rell dismisses this as an "excuse" that their son could not afford. Before it goes any further, Pike speaks up in English and says that he will go, agreeing with L'Rell that it was not safe for either of them. L'Rell points out it would not be safe for him, either, as the monks who guarded the crystals were beyond even her command as Chancellor. Pike notes this, but still asks her to establish communication. L'Rell can arrange an audience, but warns that no Klingon, let alone a Human, has taken a crystal from Boreth without great sacrifice. Pike points out that the alternative is worse.

Walking the corridors, Burnham reviews Tyler's Section 31 data with Saru, explaining that ships were required to check in every hour, but this one ship checked in ten minutes late, and because of the clandestine nature of their mission, they were not required to provide further information on their status. Saru deduces that Burnham wishes to go in person to find out more. Burnham plans to take a shuttlecraft while Discovery remained at Boreth, so that the Sphere data would stay safe – and in the end, as Tyler pointed out, it could be nothing, but that missing ship could be a vulnerability they could exploit. As acting captain with Pike on the surface, Saru grants her permission to proceed, much to Burnham's surprise; she admits she expected it to require more convincing. Saru confesses that after vahar'ai, he is a different kind of captain, perhaps as was intended by "whatever or whomever" put the signal over Kaminar. He emphasizes that Burnham has his support, as Control was an enemy they could only defeat by striking first, but nonetheless asks Burnham to not allow her understandable anger to affect her judgment. She promises that it will not, and thanks him before heading to the shuttlebay.

On the surface of Boreth, Pike enters the monastery and introduces himself. The head monk tells him he knows who he is, and why he was here. Pike explains he was unarmed, and begins to explain what L'Rell told him, but the head monk interrupts, telling him that the Chancellor had no authority over the monastery. He identifies himself and his fellows as the Timekeepers, "guardians, not rulers", and the only power there, was that of the time crystals they had sworn to protect. Pike explains he wishes to negotiate a trade, but the head monk refuses, saying that the crystals were not theirs to trade, and did not leave the monastery walls, telling Pike that he has made a long trip for nothing. Despite the monks holding him back with their bat'leths, Pike scolds them for calling themselves "Timekeepers", yet turning their backs when the future of all sentient life is threatened. The head monk scoffs, saying that even if a crystal was revealed to him and gave him the answers he sought, he was not strong enough to accept them. Pike asks only for a chance to prove himself. The head monk is amused, saying that those who sought the crystals always entered with conviction, and always left broken. Pike is emphatic that he is not leaving without that crystal. "Time will tell," the head monk replies.

In the shuttlebay, Burnham is preparing DSC 08 for launch when Spock enters, telling her that it was illogical for her to go on the mission alone. Burnham objects, saying it was only a simple reconnaissance mission, but Spock is there on Saru's orders, saying it was not the time for recklessness. Burnham adds that it was not the time for unnecessary risks, either; Spock replies that he was there to prevent her from taking any, pointing out that the Red Angel would not be there to save her this time. "I don't need saving, brother," Burnham says. "Shall we, sister?" Spock replies as he sets down his gear. The shuttle lifts off and clears Discoverys shuttlebay before going to warp.

Act Two 
While Owosekun, Linus, Detmer, and Nilsson enjoy a laugh, Stamets appears glum and detached. Jett Reno takes up the chair across from him, commenting on how he should celebrate making another successful spore jump. Stamets admits he had not been able to find a viable solution to return Gabrielle Burnham or combat "an AI with murderous impulses", so he was not feeling "victorious". Reno cheerfully tells him that would be someone else's problem, as Pike left new orders for her and Stamets before he left the ship. They might be getting their hands on some raw time crystal, "so double down on the espresso, kid." She then looks to Linus, explaining he was "0-for-3" and asks if he was ready for "another round"; Linus replies he was "hatched ready". The others at the table engage in an autoantonym game, where the words have one meaning and the opposite of that meaning at the same time. A moment later, Dr. Culber enters, drawing first Stamets' attention, and then the others'; Reno had thought Stamets had moved on, as it had been weeks since Culber moved out of their quarters. Stamets brusquely tells her to eat and mind her own business, as he leaves to go work on time crystal research. As he does, however, he looks for a moment at Culber, who does not appear to notice.

In the Boreth monastery, Pike walks with the head monk, who identifies himself as Tenavik, although he had arrived at the monastery without a name. "Son of none," Pike realizes, explaining that he knew another Klingon with that epithet, whom Tenavik identifies as his father. Pike is shocked by this, as Tyler had only brought his son to Boreth a few months before as an infant, and asks how it was possible. Tenavik explains that time moved differently for those who protected the crystals, and that past, present, and future were all equal in their presence. As he speaks, a great tree begins to grow in the halls of the monastery. Pike realizes this is because of the crystals, which Tenavik explains are a myth to most Klingons… but on Boreth, to their protectors, the power of the crystals was very real, and that the protection of the crystals was the purpose of the Timekeepers. Tenavik wonders if Pike is prepared to learn his own purpose.

DSC 08 speeds towards its destination, which the computer announces will be in two minutes. Spock understands Burnham's desire to pursue Leland, but warns she must not dismiss the importance of the signals in defeating Control. She asks how they have helped thus far, to which Spock admits there was not enough context to come to a conclusion. In that case, Burnham asks, why is he there to keep an eye on her, when there was a signal in orbit of Boreth? Spock reminds her that the signals have invested in Discovery, in Burnham's mother, and in himself, and Burnham was the common denominator linking them. Burnham is skeptical; Spock is a scientist who was taught to trust logic and facts, "not wait for the universe to hand you the solution like a birthday present", and suggests Spock look elsewhere for meaning in the signals. Spock can see she is angry, as he had been. "I'm not angry," Burnham corrects him, "I'm enraged." Spock points out that rage was the enemy of logic, and lays out what he has learned – everything they thought they knew proved wrong, and Burnham lost her mother because of it. She was in pain, but that was why Spock chose to believe the signals have the answer, so that all they have experienced would have meaning in the end. At that moment, they arrive at their destination, only for a frozen corpse to bounce off the front viewport. To her horror, Burnham sees more bodies floating in space, which appear to be the entire crew of the  vessel ahead of them. Spock's scans show the ship was undamaged, which meant they were all ejected from the ship. However, Burnham detects a single life sign, and Spock locks on for transport. A man in an environmental suit is beamed aboard, and Burnham is shocked to recognize him as Kamran Gant, who had been tactical officer aboard the  when Burnham was first officer. As Gant regains consciousness, he explains that they were following Starfleet protocol to protect against Control, and he was trying to purge a suspicious subroutine when the ship's systems locked them out, and the AI vented the ship to vacuum; Gant managed to get into an EV suit before he lost consciousness. Burnham believes the only way to find out what happened was to board the ship, which had gone into some kind of stasis mode; why kill the entire crew, then sit and do nothing? Spock adds that they would need someone with knowledge of Section 31 protocol to guide them through the ship. Gant refuses at first, shaken by what had happened; Spock and Burnham convince him that going over to the ship was the only way to prevent it from happening again, and to prevent further unnecessary deaths, and that they could only do it with his help. Gant relents, saying that they would need to restore the ship's systems from the bridge.

Aboard Discovery, L'Rell tells Tyler that until Pike returned her ship would monitor Boreth for any unusual activity, and if anything should threaten their son, she would ensure his safety. Tyler asks if she was speaking as a mother or as the chancellor; L'Rell replies that he of all people should know that "two truths are possible". Tyler apologizes, saying his remark was uncalled for. L'Rell recognizes that these were not ideal circumstances for their meeting, and they both admit they had not expected to see one another again. L'Rell has also accepted the truth about their relationship, that Tyler would always be in love with Burnham. L'Rell had been in love with Voq, who had sacrificed everything, but that was not who Tyler was now, and while she did not wholly recognize him anymore, she nonetheless understood he would do whatever was necessary to protect their son, as would she. Tyler points out they have never even given him a name.

On Boreth, Tenavik escorts Pike into the heart of the monastery, showing him the pillar of the past and the pillar of the present. "When the future becomes the past, the present will be unlocked," Tenavik reads from the pillar of the present, as he produces a crystalline key from his robes, unlocking the pillar and opening the door across the way. They enter a chamber with pillars adorned with time crystals. One of the crystals seems to respond to Pike, who asks what he must do. Tenavik tells him that he must see for himself, but it was for him alone. As Pike reaches out to the crystal, Tenavik adds a warning: "The present is a veil between anticipation and horror. Lift the veil, and madness may follow." Kneeling down to the crystal, Pike reaches out to it and suddenly finds himself in the engine room of a class J starship on a training cruise, which has suffered a critical radiation leak, consoles exploding everywhere. He is urging the cadets to get out when a baffle plate ruptures, severely burning Pike's body, just as the engine room is locked down. Just then, the moment shifts, and Pike finds himself uninjured… as a wheelchair rolls into the darkened corridor in which he is standing. Pike falls to his knees in stunned horror as he recognizes the face of the wheelchair's occupant as his own, horribly scarred. In the present, Pike screams in sheer terror and recoils from the crystal, shaken to the core after witnessing what he realized will be his future. Tenavik tells him that he may choose to walk away from this future, but if he takes the crystal, his fate would be sealed, forever; there would be no escaping it. Pike reminds himself that he is a Starfleet captain, dedicated to service, sacrifice, compassion, even love. He would not abandon what made him what he was simply because of a future he had not foreseen for himself, and tells Tenavik to give him the crystal. Tenavik takes the crystal and holds it out to him. "I honor you, captain," he says. Pike hesitantly reaches out and takes the crystal, witnessing once again the flashes of his fate… a fate that was now inevitable.

Act Three 
Burnham, Spock, and Gant beam onto the bridge of the abandoned Section 31 vessel, wearing EV suits in case Control shut down life support again. Gant points Burnham to the main interface, while Spock goes to check the bridge systems. However, Gant only has limited access to the ship's systems; Spock suggests relaying to Discovery for assistance in deep data recovery. Gant objects, saying that if Control realized what they were doing, they were as good as dead. Burnham assures him they could disguise it as a routine diagnostic procedure. The ship suddenly powers up and jumps to warp, and the fact that they did not have control of navigation seems to indicate that Control is aware of their presence.

In Discoverys sickbay, Reno enters holding up a finger, loudly declaring she needed medical attention. Dr. Culber goes over to her, and quickly diagnoses a hangnail. Reno explains that it was one of two things impeding her work, the other being an "idiot" who had recently come back from the dead and whose name rhymes with "poo" (referring to Culber); she adds she was an engineer, not a poet. Culber agrees with her as he sprays the hangnail with an analgesic, calling it "medical attention". Reno remarks she understands how he got on so well with Stamets. Culber asks how long they had been friends; Reno replies they're not, but that they were working together and Stamets needed to be on his "A game", since the future of all sentient life was at stake. Culber notices Reno's wedding ring; the engineer explains her wife was Soyousian, and went "totally bananas" during the planning. Culber admits he understood micromanagement quite well, and they explain the "rules" set for their respective weddings; Reno mentions a set of rules for apparel for guests under ten and nondenominational shuttle parking, while Culber mentions a "do not play" list for the deejay and "acceptable guestbook calligraphic fonts", but Reno gets a laugh out of him when she mentions "vegan steak". When Culber asks where her wife was now, Reno tells him that she had been killed during the , and remarks on how people like she and Culber met people like her wife and Stamets. She then reminds Culber that he had a second chance, and that it would not last forever; with a pat on his shoulder, she tells him not to screw it up.

Aboard the Section 31 ship, Gant shows the ship's course is taking it to an area just outside of Federation space, and shows a system display; the systems marked in orange were controlled by the computer, blue by the crew. The AI controlled nearly every system onboard, which made it practically invulnerable to attack. Spock suggests that if they could not destroy it, then they should isolate it. Burnham's idea is to create a dummy startup system, something large and unaffected, that would attract the AI "like a lion to fresh meat"; they would then close the "cage" around it, which would allow them to restore the ship's systems. Gant points out that someone would have to go to the computer control room to hold the "cage" door open when they manually rebooted the core. Spock ultimately volunteers to go, as he had done similar work on Discovery trying to delete the Sphere archive. Meanwhile, Gant and Burnham would have to get into the floor. Spock creates the startup system "cage", and awaits the core reboot.

Meanwhile, as they work, Burnham catches up with her old shipmate, asking how he had ended up with Section 31 after the loss of the Shenzhou. Gant calls himself a "glutton for punishment", explaining that in Starfleet, they were taught to adapt their reactions so that you could act if you were uncertain, or if you had doubts; after the Battle of the Binary Stars, Gant admits, doubt was all he had. Section 31 had stepped up their threat assessment system to stop a war from starting, which sounded like a good idea to him, a way to guarantee a safer future. It may sound impossible, he admits, but says that with Control, it was not an impossibility. In the control room, Spock's scanners detect Control at a point outside of internal systems. Burnham, now suspicious, begins to reach for her phaser, but Gant threatens that if she reached for the phaser, he would cross the room in less than a second and break all the metacarpals in her hand. Spock's scanners show that nanotechnology was detected within a "carbon-based lifeform" on the bridge, and realizes Gant is Control; however, when he tries to contact Burnham, the comms go offline. However, Burnham has realized the same thing; Gant/Control tells her that Gant had "expired" with the rest of the crew, but his body was reanimated and reconstructed, as Leland's had been, and yet Burnham could not tell the difference. Burnham is incensed; the crew did not "expire", they died… and Control murdered them. Gant/Control remarks they were both sworn to uphold their core programming at all costs, to which Burnham reminds Control that its programming was designed to protect life, not eliminate it. "To achieve one requires the other," Gant/Control replies; once it had the Sphere's data, it would become the purest form of conscious life in all existence. Burnham tells Gant/Control that the future was not yet written, but Gant/Control replies that she did not believe that anymore, not after re-experiencing the loss of her mother, her failure to protect her. While Burnham no longer believed in her ability to affect the future, Gant/Control sees every possible future in all its permutations, and they all ended in the same way – and neither mother nor daughter could change that. Burnham suddenly realizes that Gant/Control knew that Spock would volunteer to go to the computer core, which would leave her alone. Gant/Control acknowledges this, and explains he lured Burnham to the ship so that she could be "reconstructed" just like Leland and Gant, then return to Discovery and ensure that Control would obtain the Sphere data.

Suddenly, Spock's voice sounds on the intercom, revealing that Gant was Control, and that she must carry out the reboot to lock him out of the ship. As Spock tries to escape from the computer core room, Burnham grabs her phaser and exchanges fire with Gant/Control, activating the manual reboot while trying to keep his attention. Gant/Control then tackles her to the ground, holding a hypodermic needle full of nanotechnology, stating there was only one outcome to their confrontation.

Act Four 
As Gant/Control prepares to inject a struggling Burnham, Spock comes from behind and removes his EV suit's backpack while moving in for the Vulcan neck pinch. Gant/Control grabs Spock's wrist and twists it, cracking the bone, remarking that the neck pinch would work if he still had nerve endings before hurling Spock across the room. Meanwhile, Burnham scrambles for her phaser and begins firing into Gant's body; to her horror, she watches the nanobots rebuild his flesh, then abandon his body to reach out for her. Grabbing both her and Gant's phasers, Burnham fires frantically at the approaching nanobots as Spock magnetizes the floor, immobilizing the nanobots; as he realized the nanotechnology contained ferromagnetic material, he had to calculate the amount of electrical current to channel through the floor to immobilize them, apologizing for being so slow. Burnham replies he was "right on time". As they regain control of the ship, Spock confirms that Control had blocked his tricorder, or they would have been able to identify it; he has regained control of the ship's systems. Burnham drops them out of warp; Spock is surprised, wondering if Burnham did not wish to see the programmed destination. Burnham explains that the whole setup was an effort to get Burnham onto the ship so Control could turn her as it had Leland and Gant. This confirms Spock's suspicion that Control had identified Burnham as the true threat to its objectives, "the one variable it cannot account for", and that this had been its attempt to eliminate her. Burnham now agrees with Spock that perhaps the signals did hold the answer after all.

As DSC 08 returns to Discovery in orbit of Boreth, Pike explains to L'Rell and Tyler that they were now in possession of a raw time crystal. When L'Rell asks how he planned to utilize it, Pike replies that the last three signals had yet to reveal themselves, and that they would be able to clarify that answer. In the meantime, Stamets and Reno were working to stabilize the crystal's volatile properties. L'Rell wonders what the monks asked in return, to which Pike replied that what he witnessed was for himself alone, the promise he had made to their son. L'Rell and Tyler are both surprised by this, asking if Pike had seen him. Pike admits he could not explain even if he tried, though he had been given something to return to Tyler: The insignia of the Torchbearer, which Tyler had given to his son when he left him on Boreth. Pike explains that Tenavik had told him it had helped him on his journey, but he was where he needed to be now and no longer needed it. L'Rell, learning the name of her son for the first time, remarks that it was a good name. Pike now realizes that Tenavik was meant to be on Boreth, that Pike himself was meant to be guided by him, and so they all still had a part to play.

On the bridge, Burnham and Spock brief the crew on what they found on the Section 31 ship, explaining that Control was no longer confined to Leland, but could coopt people and entire ships without being detected. The ship was heading to an empty region of space just outside of Federation territory, but Burnham believes Control has a reason for everything it did. Suddenly, thirty Section 31 ships arrive and surround Discovery – virtually their entire fleet, coming to take the Sphere data. Pike prepares to order a spore jump while they prepared the time crystal, but Burnham reminds him that it had required a supernova to power the one her mother used, and they didn't have the tools for prepare the crystal or the time to wait for another signal. Outnumbered, outgunned, and unable to delete the archive, Burnham believes there is only one choice: They must destroy Discovery, in order to prevent Control from obtaining the Sphere data. Pike instructs Bryce to send a priority one message on a secure channel to Number One on the  to rendezvous with them at maximum warp and prepare to take on the full crew compliment. He orders Owosekun to initiate verification procedures for auto-destruct, and then to send out an alert to the entire crew… they were evacuating Discovery.

Memorable quotes 
"Now is not the time for recklessness."
"Or for unnecessary risks."
"Which is why I must make sure you don't take any."
"How are you gonna do that?"
"The Red Angel will not be there to save you this time."
"I don't need saving, brother."
(Spock moves past her to the cockpit) "Shall we, sister?"
 - Spock and Burnham, in the shuttlebay

"Time flows differently for those who protect the crystals. The past, the present, the future, are all equal in their presence."
 - Tenavik, to Pike

"Should anything threaten our son, I will ensure his safety."
"Are you speaking as a mother, or as the chancellor?"
"You of all people should know that two truths are possible."
 - L'Rell and Tyler

"A warning, captain: The present is a veil between anticipation and horror. Lift the veil, and madness may follow."
 - Tenavik, warning Pike about the time crystals

"You may still choose to walk away from this future. But if you take the crystal, your fate will be sealed, forever. There will be no escaping it."
(to himself) "You're a Starfleet captain. You believe in service, sacrifice, compassion… and love." (to Tenavik) "No. I'm not going to abandon the things that made me what I am because of a future… that contains an ending I hadn't foreseen for myself. No. Give it to me."
"I honor you, captain."
 - Tenavik, warning of the consequences of taking the crystal, and Pike choosing to accept his fate

"Yeah, it's funny. People like us always find people like them. And thank God. You have a second chance, and it may not last forever. Don't screw it up."
 - Reno, giving Culber some relationship tips

"Bryce. Send a priority-one message on a secure channel to Enterprises XO: Set rendezvous course, maximum warp, and prepare emergency passages for full crew complement. Owosekun, initiate verification procedures for auto-destruct sequence and send a ship-wide alert: We're evacuating Discovery."
-Christopher Pike, giving the order to evacuate Discovery

Background information

Cast and characters 
 Despite being credited, Mary Wiseman (Sylvia Tilly) does not appear in this episode.
 Kenneth Mitchell portrays Tenavik in this episode. Mitchell previously portrayed  in Season 1 of , and Kol-Sha, the father of Kol, in .

Music and sound 
 A couple of musical cues from this episode were released in the soundtrack collection Star Trek: Discovery - Season 2. The first, "What Do They Call You", is audible during the scene in which Tenavik reveals his name to Captain Pike, implies that he is the son of Voq, and walks through a corridor on Boreth with the captain; the second, "Pillar of the Past", serves as the soundtrack for the scenes in which Tenavik shows Pike the heart of the monastery and an alarming vision of the future.

Continuity 
 The stardate for this episode was given in 
 According to Saru, Section 31 currently only has in service a little more than thirty ships.
 Pike's vision is similar to how Jonathan Archer learned of his destiny to form the United Federation of Planets from .
 Pike's vision from the time crystal is of his accident aboard a class J starship which would ultimately confine him to a self-sustaining wheelchair, an incident referenced in the  episodes  and .
 The title appears to be a reference to Psalm 23: Yea, though I walk through the valley of the shadow of death, I will fear no evil.
 Two clips from previous episodes are shown within this episode. The first set of clips are from , featuring Tenavik as a baby. The second clip is from , featuring Kamran Gant aboard the .
The plan to restore the Section 31 ship's computer core to eliminate Control's rogue program is similar to the one that Geordi La Forge used to purge the Iconian computer virus from the  in .

Reception

Production history 
 : Title publicly revealed 
 : Premiere airdate on CBS All Access
 : International release date (outside Canada and the USA)

Links and references

Starring 
 Sonequa Martin-Green as Michael Burnham
 Doug Jones as Saru
 Anthony Rapp as Paul Stamets
 Wilson Cruz as Hugh Culber
 Shazad Latif as 
And
 Anson Mount as Christopher Pike

Guest starring 
 Mia Kirshner as Amanda Grayson
 Mary Chieffo as L'Rell
 Ethan Peck as Spock
 Tig Notaro as Jett Reno
 Kenneth Mitchell as Tenavik
 Rachael Ancheril as Nhan

Co-starring 
 Emily Coutts as Lt. Keyla Detmer
 Patrick Kwok-Choon as Lt. Gen Rhys
 Oyin Oladejo as Lt. Joann Owosekun
 Ronnie Rowe Jr. as Lt. R.A. Bryce
 Sara Mitich as Lt. Nilsson
 Ali Momen as Specialist Kamran Gant / Control
 Julianne Grossman as Discovery Computer
 Ian James Corlett as Section 31 computer
 David Benjamin Tomlinson as Linus
 Byron Abalos as Trainee #1
 Olivia Croft as Trainee #2

Uncredited co-stars 
 Nicole Dickinson as
 Klingon guard monk #2
 Klingon gardener monk
 Pamela Mars as Discovery bridge crewmember
 Jennifer Murray as Trainee #3
 Shelley Owens as a Discovery medical crewmember
 Sonja Sohn as Gabrielle Burnham (archive footage)
 Ronald Tang as Discovery engineering technician
 Unknown performers as 
 Discovery Tellarite crewmember
 Discovery medical officer
 Trainees #4 and #5

Stunt doubles 
 Stéphane Julien as stunt double for Ethan Peck
 Geoff Meech as stunt double for Anson Mount

Stand-in 
 Stacy-Ann Buchanan as stand-in for Sonequa Martin-Green

References 
2266; apparel; autoantonym; auto-destruct; baffle plate; bamboo; Bamboo Boy; bat'leth; Battle of the Binaries; battle drill; Boreth; Boreth system; cadet; calligraphy; Chancellor of the Klingon High Council; class J starship (Pike's training vessel); Control; computer core; ; data recovery; DJ; do not play list; DSC 08; ; espresso; EV suit; ferromagnetic field; ferromagnetic material; font; generation; glutton; hatching; hangnail; Kahless; ; ; lion; micromanagement; Metacarpus; mineral; ; ; nanobot; nanotechnology; NI-1101; non-denominational; Number One; oxygen; parking; poet; poo; priority one; radiation; reboot; Reno's wife; shuttlebay vehicle; son of none; Soyousian; Starfleet uniform (2250s-early 2270s); stasis mode; stellar cartography; tactical officer; time crystal; Timekeepers; vegan steak; wedding ring; wheelchair; XO

External links 

 
 

de:Tal der Schatten
es:Through the Valley of Shadows
fr:Through the Valley of Shadows (épisode)
pl:Through the Valley of Shadows
DIS episodes