(written from a Production point of view)
Lorca plans to move forward with a coup against the Emperor, propelling Burnham to make a quick decision to save not only herself, but the USS Discovery.
- 1 Summary
- 2 Memorable quotes
- 3 Log entries
- 4 Background information
- 5 Links and references
In the mirror universe, aboard the Terran emperor's flagship, the ISS Charon, Gabriel Lorca frees his followers from a chamber filled with agony booths, including his loyal partner Commander Ellen Landry. Lorca and his men seek out Paul Stamets and use his bioweapon to start killing the Emperor's crew.
The Emperor is informed of the casualties of her crew. Michael Burnham advises her to allow her to contact USS Discovery again, but the Emperor does not agree and decides to imprison her in the brig. Burnham is forced to flee and escapes through a small hole in the wall.
Aboard the Charon, Lorca taunts Georgiou, and invites her crew to join his rebellion to preserve the empire. Georgiou identifies his location in the main labs, and leads her troops to "take the fight to him."
Emperor Georgiou's forces come head to head with those of Lorca, after which she alone escapes being killed using an emergency transport system. Lorca orders Stamets to kill the emergency transport system and they secure the throne room.
Burnham accesses the Charon's communications system to contact the Discovery, warning them that Lorca is in fact from the mirror universe. The crew convey the importance of bringing down the containment field around the energy orb powering the palace ship. Burnham promises to take down the containment field.
Entering the throne room, Lorca's confidence that fate had brought him to this point grows, before killing the mirror universe Stamets. Landry is informed of the ship-to-ship transmission.
Lorca tracks Burnham to level 3, and attempts to convince her to join him in his rebellion against the emperor by describing his past with the Burnham from his universe. Landry attempts to capture her while Lorca is distracting her, only to find Burnham had rerouted the communications feed masking her location.
The emperor, too, is thinking back to her relationship with the mirror Burnham, when Commander Burnham finds her. Burnham explains the parallels between her betrayal of her Georgiou, and the mirror Burnham's betrayal of the emperor. Together, the two discuss the plan to defeat Lorca.
Aboard Discovery, the crew discuss options to destroy the energy orb, but the only option seems as though it will also result in the Discovery's destruction. Saru rallies the senior officers, indicating he does not sense death in their future and that they will defeat this "no-win scenario."
In the throne room aboard the Charon, Landry reports to Lorca that the emperor's crew has either been killed or joined their movement. Lorca's guards capture and bring Burnham and Georgiou to Lorca. Burnham agrees to offer Georgiou and herself, her mind only, in exchange for letting Discovery return to their universe.
Tilly and Stamets discover a way to escape destruction, if they ride the mycelial explosion in conjunction with the warp drive.
Discovery receives a message from the Charon and drops out of warp, then receives a hail from Lorca. Burnham sends a coded indicator to attack, and the Discovery launches its attack, kicking off a hand-to-hand battle between Lorca and Georgiou, and Burnham and Landry. Georgiou eventually defeats Lorca by stabbing him through the heart with her sword, before kicking him through a force field out into space to be vaporized in the ship's mycelial sun.
With Lorca defeated, Georgiou prepares to buy Burnham time by fighting off Lorca's remaining followers. Burnham grabs Georgiou, pulling her into the transporter beam and bringing her to Discovery.
Discovery attacks the Charon's energy orb – setting off the mycelial shockwave, which Discovery combines with its strategy to jump to warp to ride back to the prime universe. Stamets struggles to navigate the recovering mycelial network until he can remember Hugh's advice.
Discovery seeks to confirm the date and location they've returned to, with no response from Starfleet. Stamets finds that they've returned nine months ahead of the point that they left, to which Saru immediately asks Rhys to update their map of the war effort. The map reveals a major expansion of Klingon territory, with Starfleet having all but lost.
"One year, 212 days of torture... of agony, my friends... my followers. But I have returned to give meaning to your suffering. Today is the day we reclaim our empire!"
- - Gabriel Lorca
"Gabriel! I really hoped you were dead."
"Well, you can't always get what you want."
- - Gabriel Lorca and Paul Stamets
"Hello, Philippa. I've watched for years; you let alien races spill over the borders, flourish in our backyard, then have the gall to incite rebellion. The Terrans need a leader who will preserve our way of life, our race. Try as you might, it's clearly not you. Even Michael knew that. It was her great shame. Well, it's indecorous of me to share pillow talk. To the rest, many of you know me. Some of you served with me. To all, I make this offer; renounce Georgiou. The Empire is dying in her hands. But you don't have to- not today. Michael Burnham is not to be touched. She is integral to our future plans. A future where we together will make the Empire glorious again."
- - Gabriel Lorca, inciting another coup against Emperor Georgiou
"Believe in destiny now, Mr. Stamets?"
"That's uh, rhetorical, right?"
"Your lack of vision continues to disappoint me. I used to suffer from that, too. But nothing that's happened to me was an accident. Not ending up in another world, not finding a ship that would help me return here. None of it. I'm living proof that fate is real."
- - Gabriel Lorca and Paul Stamets
"It's poetic justice, don't you think? A scientist destroyed by his own creation? Just kidding. I hate poetry."
- - Gabriel Lorca, moments before he has mirror Paul Stamets executed
"You lost a daughter. An empire. I lost a captain, and a life."
- - Michael Burnham
"I was just thinking about everyone who's ever said that victory felt empty when it was attained. What a bunch of idiots they were."
- - Gabriel Lorca
"It is well known that my species has the ability to sense the coming of death. I do not sense it today. I may not have all the answers; however, I do know that I am surrounded by a team I trust. The finest a captain could ever hope to command. Lorca abused our idealism. And make no mistake, Discovery is no longer Lorca's. She is ours. And today will be her maiden voyage. We have a duty to perform, and we will not accept a no-win scenario. You have your orders. On your way."
- - Saru
"I am a defeated emperor. They've seen my neck. I have no future now. But I will die on my feet as fitting my station."
- - Philippa Georgiou
"What the hell are they doing?… Is the containment field up?!"
- - Ellen Landry, seconds before the Discovery destroys the Charon
- - Paul Stamets, as he navigates Discovery back to their own universe
- "Captain's log, stardate 1834.2. Acting Captain Saru recording. We are en route to the Terran flagship, having been summoned by Specialist Burnham. Discovery's spore drive is operational again, thanks to the full recovery of our navigator, Lieutenant Stamets. Yet, despite his best efforts, the lieutenant was unable to save Discovery's mycelium crop. His fear is that his Terran counterpart has already contaminated the network, and if so, the results could be catastrophic."
- "What's past is prologue" is a phrase from Act 2, Scene I of William Shakespeare's The Tempest. It also inspired the title of the Star Trek: Deep Space Nine episode "Past Prologue" as well as Jake Sisko's story "Past Prologue" in DS9: "The Ascent" and the Pocket TOS novel Past Prologue.
- Precisely when to return from the mirror universe was the subject of considerable discussion amongst the writing staff of Star Trek: Discovery. Erika Lippoldt recalled, "There was a point we were considering doing more [in the mirror universe], but it was really the fact that we had fifteen episodes and that we didn't get to mirror until ten that, like, we just ran out of road [….] And so, it was just the way things laid out [….] Basically, by the time you get to episode ten and you are aiming for that endpoint where you're kinda gonna resolve [things in the prime universe], that doesn't leave much wiggle room for, you know, staying in mirror longer, but certainly it was like early, early days, we were like, 'Maybe we can stay there longer.'" 
- During the breaking of the story for probably either this episode or the previous one, Kirsten Beyer noticed – when she was in the DIS writers' room with Bo Yeon Kim, Erika Lippoldt and Lisa Randolph – that it was a historically significant moment, due to there being an all-female writers' room. "I thought to myself, 'I believe this is the first time four women have sat around and decided what the future of Star Trek was with nobody else in the room,'" Beyer recalled. "It was a unique moment in history for sure, and I was very much aware of it." ("A Woman's Journey", DIS Season 1 & Blu-ray special features)
- While writing this installment, Co-Executive Producer and writer Ted Sullivan was inspired by the film Die Hard. "In breaking this episode, there were a lot of points where I was like, 'Wait a second! There's stuff that seems to echo Die Hard' [….] [Burnham] is crawling around in air ducts. There's the conversation between Burnham and Lorca over basically a cell phone, which, you know, in Die Hard, it's Hans Gruber and John McClane over the walkie-talkie. So, I wanted to have those types of moments." Taking inspiration from Die Hard also made sense to Sullivan because he was a big fan of the film in general, so he was eager to make Lorca slightly more like the villainous Hans Gruber. (AT: "What's Past Is Prologue")
- The idea of using this episode to bring back the character of Landry, albeit the mirror-universe version, was thought up by Ted Sullivan. There were two reasons he wanted to incorporate her into the plot, the first of which was that he wanted to work with Landry actress Rekha Sharma, who he hadn't had a chance to work with before. The other reason was that he believed the relationship between Lorca and Landry would be very close and, like Burnham's connection with Georgiou, universe-transcending. Sullivan also believed that the way Burnham and Georgiou's relationship crossed universes was why they teamed up against Lorca. (AT: "What's Past Is Prologue")
- Although the concept of the Charon containing a small sun had been invented by Production Designer Tamara Deverell, she found it was included in this episode's narrative. "The writers took that and made it part of the story," she reflected. ("Designing Discovery", DIS Season 1 DVD & Blu-ray special features) Deverell elaborated, "When they saw the initial sketches [of the Charon], the writers and producers loved this idea of it having its own sun and were inspired to take it one step further in the writing room. The solar power source became the mycelial sun that ran the ship. It was also part of the Terran abuse of mycelial power, as well as the […] way that Terran Captain Lorca would die, falling into this core." (Star Trek: Discovery Designing Starships, p. 184)
- Lorca actor Jason Isaacs worked with Ted Sullivan on the speech that Lorca gives, in an effort to make it personally relatable as well as a close approximation to what many people in the world think. Recalled Sullivan, "Jason and I actually spent a lot of time talking about those types of speeches [….] And one of the things Jason was so good about on the set was to really push us and push me to say… I mean, we got into [his] trailer and sat down with a computer and worked on that speech a lot, and the reason why we did that is we felt we had a unique opportunity to talk about what's going on in the world right now, and that's what Star Trek is supposed to do." They wanted the speech, in which he talks about the Federation as a failed social experiment, to resonate with modern audiences in a way they could identify with it as reflecting "the worst part of ourselves if we're not careful," explained Isaacs. (AT: "What's Past Is Prologue")
- Ted Sullivan wrote the speech Saru delivers to the crew about not accepting a no-win scenario. "For me, as a lifelong Star Trek fan," he said, "it was an opportunity to lean into the ideology of Starfleet, the ideology of what I love so much about Star Trek, and to finally, after thirteen episodes, give the fans the moment that says, 'No, we get it. We believe in Star Trek and Starfleet, too. We just had to go through this journey for twelve episodes.'" The scene additionally enabled Sullivan to include the members of the Discovery bridge crew, which he wanted to do in order to show them uniting. (AT: "What's Past Is Prologue")
- In the final space battle, Ted Sullivan purposefully included many moments where members of the bridge crew exchange looks. This was because he was interested in showing them finally working as a family-like team, having been united by Saru's speech. "That was very, very intentional," he acknowledged. (AT: "What's Past Is Prologue")
Cast and characters
- Sonequa Martin-Green described this installment as "a truly outstanding episode." (AT: "What's Past Is Prologue")
- Michelle Yeoh liked the way that the fight scene between her character of Emperor Georgiou and Mirror Lorca was "not a stylized fight" and instead was "really two hardcore Terran warriors just going for it." "So, it's an interesting fight," Yeoh remarked. ("Star Trek: Discovery: The Voyage of Season 1", DIS Season 1 DVD & Blu-ray special features)
- Jason Isaacs thoroughly approved of Lorca's fighting style in his combat with Burnham. "Lorca is fighting her and just trying to contain her, like you do with an errant child. I'm trying to hold her," he explained. "If you look, I'm not trying to punch or kick or break or snap or do anything aggressive to her, 'cause I'm trying to get her to calm down and see that she's got a place here, which is slightly insane of me, but I choose not to kill her, and she thinks I wouldn't be able to." Isaacs called this fight "more glorious" than the slightly later moment when Burnham tells Lorca that, if he had asked Starfleet to help him return home, they would have assisted him. Isaacs nonetheless called that moment "glorious" and "beautiful" but, despite believing that Burnham means what she says in this moment, he was doubtful that, if Lorca had requested assistance, Starfleet would actually have been eager to help him. Regarding his opinion about Burnham believing what she says to him when she says it, Isaacs told Ted Sullivan, "That's what is interesting and great and complicated about this show and the characters you've created." Isaacs also thought it was "funny" that, whereas he played Lorca's agonizer scenes as if they were traumatic, Rekha Sharma played Landry's exit from her agonizer, after years there, as if her character had much less of a problem dealing with the ordeal she'd faced. Saru's speech to the crew was a highlight for Isaacs; he not only called it "a beautiful speech and incredibly moving" but was also very impressed with how Doug Jones performed the monologue in his role of Saru, given that the character's Kelpien makeup was highly restrictive. (AT: "What's Past Is Prologue")
- In Rekha Sharma's opinion, something that was "wonderful that Ted [Sullivan] created in our mirror episode" was the moral that "you can't, you know, point the finger when you can actually root for somebody, when you can see both sides of the equation." Additionally, Sharma described the scene in which Burnham is crawling inside one of the ISS Charon's Jefferies tubes as "incredible." (AT: "What's Past Is Prologue")
- Shazad Latif (Ash Tyler) does not appear in this episode.
- The approach of the Discovery towards the Charon in the episode's climactic moments, before the Discovery flew through the larger vessel, was illustrated in a concept image. (Star Trek: Discovery Designing Starships, p. 181)
- One move which was originally part of the climactic fight scene in the Charon's throne room was deliberately not used. Jason Isaacs recalled, "Rekha and I had a moment in the fight that we choreographed where she was locked up with Burnham and she had her back to me, and in order to try to get to Burnham, I'd stabbed right through Landry […] And at the last minute, we cut that move because we realized, 'I don't want to kill Burnham.' It was never because I wouldn't have sacrificed Landry for Burnham, and I think it was a moment for Burnham and Lorca, and it was a moment for Jason and Rekha, that she went, 'You'd… You'd do that?' I said, 'It's a good move in a fight; I'll do anything for love.'" (AT: "What's Past Is Prologue")
- Doug Jones' performance of Saru's speech was well received by the cast and crew during production. "Anthony Rapp came up to me afterwards, watching him do that monologue, take after take," Ted Sullivan remembered, "and Anthony was like, 'This is special,' and I went, 'It is special.'" (AT: "What's Past Is Prologue")
- For Rhys actor Patrick Kwok-Choon, the filming of Lorca's death scene was highly memorable. "I still remember seeing Jason [Isaacs] suspended in the air in the distance in front of this huge green screen, just twirling, twirling, twirling, before he got incinerated by the orb," Kwok-Choon recalled. "When his final take was finished, we all started chanting, 'Bring back Lorca! Bring back Lorca!'" (AT: "Will You Take My Hand?")
- The single spore that lands on Tilly's shoulder was puzzling for actress Mary Wiseman when the episode was being filmed. "Mary Wiseman came up to me on the set and goes, 'Hey, what's up with that spore?'" reflected Ted Sullivan. "I'm like, 'Ah… Wait til Season 2.'" (AT: "What's Past Is Prologue")
- During the making of this episode, Rekha Sharma enjoyed watching Ted Sullivan and Director Olatunde Osunsanmi collaborate with each other. "I liked calling them 'T-squared'," she noted. Sharma was also amazed by Osunsanmi's work on this episode in general, calling it "unbelievable." (AT: "What's Past Is Prologue")
Music and sound
- When Composer Jeff Russo first began writing music for Star Trek: Discovery, how this episode would end was one aspect he didn't yet know, because the installment's conclusion hadn't been scripted yet.  He recorded the episode's score on Friday 8 December 2017. 
- A few musical cues from this episode were released in the soundtrack collections Star Trek: Discovery - Season 1, Chapter 2 and Star Trek: Discovery - Season 1, Chapters 1 & 2. The first, "212 Days of Torture", provides the soundtrack for the sequence in which Lorca frees his followers from their agony booths and reunites with Landry; the second, "Biotoxins", accompanies the scenes in which some members of Emperor Georgiou's crew suffer a biological attack, and she converses with Burnham, who then manages to escape; the third, "Come in Discovery", accompanies Burnham attempting to contact her ship; the fourth, "Safe to Drop Out of Warp", serves as the soundtrack for the Discovery's rendezvous with the Charon and the fight between Lorca, Georgiou, Landry and Burnham; the fifth, "Lorca is Finished", provides the soundtrack for Lorca's death, followed by Burnham and Georgiou transporting to the Charon; and, finally, the sixth, "Coming Home", plays over the Discovery's departure from the mirror universe until the point Stamets begins to perceive a route through the mycelial network.
- A couple of segments of footage were deleted from this episode. These portions of footage are included on the DIS Season 1 DVD and Blu-ray.
- The first deleted scene, omitted from the start of the episode, involved a bloodied Lorca stepping over Captain Maddox's deceased body, next turning off the agonizers, and then proceeding to deliver some of the speech he gives to his followers. Lorca declared, "They hunted us, tortured us, chased us to the edge of the galaxy and beyond. But in their hubris, they did not kill us. Why? To send… a message. The only message they sent was their fear and their weakness. We will not make that same mistake. We will take what is ours, my friends, and we will make the empire glorious again." Then, the agonizers all systematically turned from red to blue and each of their doors opened, although the visual effects shot to portray this moment wasn't finished.
- Another moment which was significantly altered was a different version of the scene where Stamets enters the cultivation bay. This alternate version of the scene had no visual effects but did have a temporary, entirely different captain's log voice-over by Saru. In it, he stated, "Travel is impossible. The reason: an infection that has corrupted our mushroom stores and the mycelial network itself. I can only hope that Burnham and Captain Lorca have found us another way home. Because without it, we may be trapped in this ghastly universe forever." In the final version of the same scene, Saru's voice-over instead comments, "[…] the full recovery of our navigator, Lieutenant Stamets. Yet, despite his best efforts, the lieutenant was unable to save Discovery's mycelium crop. His fear is that his Terran counterpart has already contaminated the network. And, if so, the results could be catastrophic."
- The alternate version of Stamets' walk in the cultivation bay was followed by a deleted scene between him, Tilly and Saru in the engineering test bay. As they said in their discussion, the entire mycelium crop was affected, leaving only the prototaxites stellaviatori crop. Although the team was absent a diagnosis, Stamets mentioned that "Hugh" had told him the mirror Stamets had been causing damage to the mycelial network, a statement Tilly and Saru reacted to by exchanging a concerned glance. Though Stamets tried to tell them that he had found Culber in the network, Saru implied that he didn't take this news seriously, saying only that he and the rest of the crew also missed Culber. The discussion between Saru and Stamets became more official and slightly more taught. As Discovery was to reach the Charon in slightly less than an hour, Stamets asked Saru to route him all the long-range sensor data on the Charon, so that they could determine what was happening there in a last-ditch attempt to be able to use the spore drive again.
Continuity and trivia
- Counting the Klingon facade of Ash Tyler as a Klingon character, this is the first Discovery episode that does not feature any Klingons.
- The mirror Gabriel Lorca arrived in the prime universe via a transporter accident the same way Kirk, McCoy, Scott, and Uhura entered the mirror universe in 2267; in Lorca's case, it was while beaming up to ISS Buran during an ion storm.
- This is the third episode of the series without a teaser, after "Magic to Make the Sanest Man Go Mad" and "Si Vis Pacem, Para Bellum".
- This episode marks the first time a main character who is a commanding officer has been written out of their series of origin.
- The mirror universe Michael Burnham's serial number, SHN4790 4600CS, mostly mirrors the prime universe Burnham's Starfleet serial number: SC0064-0974SHN.
- Ted Sullivan believed that the evolution of the prime-universe Burnham character was highlighted by her line to Lorca that, if he had asked Starfleet to help him return home, they would have helped. "I think that it shows a growth from where she was in episode one and two," remarked Sullivan. (AT: "What's Past Is Prologue") Sonequa Martin-Green expressed the same opinion about when Burnham tells Lorca she won't kill him because she's Starfleet. (AT: "Will You Take My Hand?")
- After Trek host Matt Mira likened Burnham taking hold of Emperor Georgiou, just before beam-out, to "Captain Kirk trying to save some whales," as happens in the film Star Trek IV: The Voyage Home. (AT: "The War Without, The War Within")
- The visual effect of the inter-universe mycelial travel bears a certain resemblance to the Slipstream travel in the TV show Gene Roddenberry's Andromeda – the animation as well as the "Shake, Rattle 'n' Roll". The score of that scene (classical-style aria) also bears a similarity to a similar scene (return to the prime universe after a longer stay in another universe) in the Andromeda episode "The Heart of The Journey (Part 1)".
- The day after Doug Jones filmed the scene where Saru delivers a unifying speech to the crew, Anthony Rapp spoke about that scene at a fan Expo in Toronto that he, Jason Isaacs and Ted Sullivan attended. Recalled Sullivan, "Anthony actually said on stage, 'You're gonna see Doug do this amazing thing through all of this rubber, and it's an amazing, emotional speech.'" (AT: "What's Past Is Prologue")
- AT: "What's Past Is Prologue" discusses the making of, and events in, this episode. A week prior to the release of this installment, AT: "Vaulting Ambition" debuted the initial conversation between Lorca and Landry from this episode.
- Ted Sullivan was pleased with Rekha Sharma's work on this installment, stating, "There's a lot of great moments that Rekha does in the episode [….] What I love so much about her performance in this episode is she infuses all of that with looks, there's looks between her and Lorca where it was scripted that she gives Lorca a look but she infused it with all of that kind of subtext, which I think is great. And it kind of comes through and helps infuse the scene in a way that… I don't know if it was there on the page, but that's what you hope for as a writer, that someone [elevates what you've written]." Sullivan was happy with the moment Burnham tells Lorca that Starfleet would have helped him get back to the mirror universe if he'd requested their assistance. "It's one of my favorite moments in the episode [….] I think it's really important that she doesn't kill Lorca in that moment," Sullivan noted. He was also enormously proud of the speech Saru gives about refusing to accept a no-win scenario. "That's actually my favorite thing I've ever done in my professional career," he commented, to which the After Trek audience responded with applause. He added, "Doug Jones was amazing on set." Another of the creative personnel whose work on this episode thrilled Sullivan was Olatunde Osunsanmi, about whom Sullivan remarked, "[He] did an unbelievable job directing this episode [….] It was an honor working with him [….] He made this episode." (AT: "What's Past Is Prologue")
- Tamara Deverell was happy that this episode's narrative incorporated the Charon's super-mycelial reactor. "[It] was the kind of thing that is just your dream as a production designer," she enthused. ("Designing Discovery", DIS Season 1 DVD & Blu-ray special features) Deverell also stated, "I loved that the design inspired the writers to include the mycelial sun as part of the story," and described Lorca's fate, falling into the reactor, as an "epic" way to die. (Star Trek: Discovery Designing Starships, pp. 187 & 184)
- Executive Producer Gretchen J. Berg thoroughly approved of the climactic fight scene in this outing. "What an amazing fight sequence! I mean, it is so great," she raved. "Tunde did this amazing… I don't know how many people were there. Eight? Let's say eight. And it's Landry, it's Lorca, it's Burnham, and it is Michelle Yeoh, and they're all kicking some ass. I could watch that on a loop over and over and over again." ("Star Trek: Discovery: The Voyage of Season 1", DIS Season 1 DVD & Blu-ray special features)
- Jordon Nardino called this a "wonderful" installment. (AT: "Vaulting Ambition")
- Aron Eisenberg and Garrett Wang were dissatisfied with a particular aspect of this episode, which was the return of the Discovery from the mirror universe. They felt the ship should have stayed there for longer, not returning to the prime universe until a much later episode. 
- Matt Mira cited this as a "fantastic episode of Discovery." He specifically described the fight scene in the throne room as "epic" and Saru's speech about not accepting a no-win scenario as "great," including "such great Star Trek'-isms." Noted Mira about the speech, "It gave me chills, it really did." On the other hand, he admitted to being saddened about Landry having died again. After watching the installment, Mira told Ted Sullivan, "There were so many shockers tonight, Ted. You really had us through the ringer, and quite frankly, thank you for that [….] I honestly think tonight's episode is one of my favorite of all time. It was really fantastic." (AT: "What's Past Is Prologue")
- Jason Isaacs commented that the uniting of the Discovery crew in this episode was "finally what the fans have wanted, when they've wondered why it doesn't seem like Starfleet because Lorca was there." (AT: "What's Past Is Prologue")
- This episode was nominated for an Emmy Award in the category of Outstanding Sound Editing for a One Hour Comedy or Drama Series.
- 8 December 2017 Score recorded by Jeff Russo 
- 13 December 2017: Title publicly revealed 
- 28 January 2018: Premiere airdate on CBS All Access
- 29 January 2018: International release date (outside Canada and the USA)
Video and DVD releases
Links and references
- Sonequa Martin-Green as Michael Burnham
- Doug Jones as Saru
- Shazad Latif as Ash Tyler
- Anthony Rapp as Paul Stamets / Paul Stamets (mirror)
- Mary Wiseman as Sylvia Tilly
Special guest star
- Emily Coutts as Keyla Detmer
- Jeremy Crittenden as Lord Eling
- Patrick Kwok-Choon as Rhys
- Sara Mitich as Airiam
- Oyin Oladejo as Joann Owosekun / Joann Owosekun (mirror)
- Ronnie Rowe Jr. as Bryce
- Bart Badzioch as ISS Charon officer
- Mustafa Bulut as ISS Charon officer
- Wilson Cruz as Hugh Culber (archive footage)
- Phi Huynh as ISS Charon officer
- Jonathan McGuire as ISS Charon officer
- Joseph Racki as ISS Charon officer
- Julie St-Louis as ISS Charon officer
- Unknown performers as Lorca's followers
- Christine Ebadi as stunt double for Rekha Sharma
- Nilo Ghajar as stunt double for Sonequa Martin-Green
- Geoff Meech as stunt double for Jason Isaacs
- Melanie Phan as stunt double for Michelle Yeoh
ability; agony booth; Alpha Quadrant; ambush; answer; battalion; Battle of the Binary Stars; bioweapon; black alert; border; brig; Buran, ISS; carrier address; Charon, ISS; clearing; containment field; coup d'état; death; emergency transport; emperor; energy dispersal; flash grenade; forest; Georgiou, Philippa; hack; Harlak; hypergravity; idealism; ion storm; leader; life sign; lord; magnetic field; maiden voyage; mirror universe; multiverse; mycelial energy; mycelial network; mycelial shockwave; mycelial spore; mycelium; nanometer; noose; no-win scenario; order; parallel universe; pathway; photon torpedo; physics; pillow talk; poetic justice; poetry; poison; Priors World; race; rebellion; revolution; sanctuary; senior officer; Starbase 46; subatomic analysis; super-mycelial reactor; superstructure; sword; terahertz; throne room; torture; transporter signature; United Federation of Planets; vaporize setting
Rhys' tactical star chart
- "What's Past Is Prologue" at StarTrek.com, the official Star Trek website
- "What's Past Is Prologue" at Memory Beta, the wiki for licensed Star Trek works
- "Discovering the Prologue" at MissionLogPodcast.com, a Roddenberry Star Trek podcast
|Mirror universe-related episodes|
|ENT: "In a Mirror, Darkly" • "In a Mirror, Darkly, Part II"|
|DIS: "Into the Forest I Go" • "Despite Yourself" • "The Wolf Inside" • "Vaulting Ambition" • "What's Past Is Prologue"|
|TOS: "Mirror, Mirror" • "The Tholian Web"|
|DS9: "Crossover" • "Through the Looking Glass" • "Shattered Mirror" • "Resurrection" • "The Emperor's New Cloak"|
|Star Trek: Discovery
"The War Without, The War Within"