Aboard the ISS Discovery, Joann Owosekun, the head of Emperor Philippa Georgiou‘s Honor Guard, throws an enraged Michael Burnham into the brig. Burnham demands that Georgiou kill her for her betrayal, as the law dictates, and tells her that every moment of hesitation will make the emperor appear weaker. Burnham posits that Georgiou has become so weak that she built the ISS Charon as a palace for her retirement. Georgiou insists that the Charon is both a legacy and something for the Terran Empire‘s subjects to live for. Burnham spits in Georgiou’s face, to what the Emperer responds that even Genghis Khan learned his grip of power couldn’t hold if he didn’t let the people he conquered worship their own gods..
The Terrans will never get spoils of war in peacetime, Burnham says. The Romulans, Klingons, Andorians, and Tellarites are forming an alliance against the Empire called the Coalition, she adds. The Denobulans, Coridanites, and Rigelians will follow and should all be attacked now. Goergiou responds that the Empire cannot fight the entire galaxy, but Burnham insists they would think twice about alliances if the Terrans flew down and roasted them on spits. But Georgiou says the rules of engagement have changed, and has Burnham thrown into the agony booth, where Owosekun tortures her.
Georgiou watches the proceedings from her quarters. Captain Sylvia Tilly enters and asks why Burnham is still using up oxygen on her ship. Georgiou insists she is not showing mercy to Burnham. Tilly responds that they must still root out her accomplices and notes that Keyla Detmer likely knew of her plans. Georgiou discloses she will have Burnham turn them in after she is broken by torture, and places Tilly in charge of the interrogation, for which she demands free reign.
A meal is slid into Burnham’s holding cell; Burnham pushes it aside violently. Tilly says she predicted to Georgiou that her daughter would not eat it, and says she will have Dr. Culber force-feed her later. The guards drag Burnham back into the agonizer, where Tilly demands she swear allegiance to Georgiou and name her co-conspirators. Burnham refuses and Tilly takes pleasure in activating the agonizer before leaving her to sleep in the device. During the night, Owosekun tortures her further. Burnham continues to reject food over time, and Culber arrives to force-feed her. At one point, Burnham awakens to find Detmer outside her cell as Georgiou observes remotely. Detmer urges her to give in and reveals that no one has heard from Gabriel Lorca, who recruited Burnham into the plot against Georgiou.
Later, Georgiou visits an unconscious Burnham and reminisces about Burnham childhood. She was quiet when awake but screamed at night in her sleep, “fighting to escape.” One night, Georgiou stopped restraining Burnham and she sleepwalked to a field of fireflies, which calmed her, allowing Georgiou to carry her back to her bed. They did that every night, but Burnham never recalled it when awake. Georgiou says she was saddened when Burnham outgrew her night terrors, though she wonders if she ever truly did. She unveils a small globe filled with fireflies and urges Burnham to trust her. She leaves and Burnham awakens, turning her head to see the fireflies. She eats a piece of bread, staring contemplatively.
Owosekun brings Burnham to Georgiou’s quarters, where Saru attends to her. She kneels and salutes, and Georgiou dismisses Owosekun and the Kelpian. Burnham apologizes and pledges allegiance, though Georgiou says she only sought to rule her empire with her daughter. Burnham offers not only to name her co-conspirators, but also to execute them herself. She hesitantly says she can be trusted again, though the emperor appears skeptical and tells her not to return until she proves herself.
Ellen Landry walks down a corridor when she is fired on by Detmer. The two trade fire briefly before Landry incapacitates Detmer. Walking away, Landry is shot by a waiting Burnham. Later, Burnham and Detmer enter Georgiou’s ready room, where Owosekun and Tilly have joined her for a drink. Burnham throws the badges of Landry, R.A. Bryce, and more than a half-dozen other conspirators, onto the table before Georgiou. Burnham then fatally stabs Detmer in front of everyone. “Now it’s done,” she says.
In Georgiou’s quarters, she and Burnham share a meal served by Saru. Burnham remarks that the kitchen has stopped serving Kelpien and Georgiou responds that Kelpien flesh is “too high in cholesterol and stringy.” Burnham says she “came to the light” weeks prior but remained in the brig out of stubbornness. She also notes Georgiou used “backchannels” to sabotage the alliance against the empire, which Georgiou says was not difficult. Burnham notes that Georgiou listened to her about the threat, and Georgiou demands she tell her the truth from now on. Burnham says she does not know where Lorca is and deflects a question about whether she still loves him, though she vows to kill him. The Emperor asks Burnham to track Lorca down.
Later, Saru brushes Georgiou’s hair as she remarks that events are unfolding as she hoped. She tells him to remain in her service rather than return to Burnham but he warns her that he is about to undergo vahar’ai and expects to die. He asks her to cull him, but she reveals that vahar’ai is not the end of his life. She instructs him to lock himself away and after a few days will find himself “changed forever.” She tells him about his prime universe counterpart, Saru, who became stronger after undergoing vahar’ai.
Saru is surprised by her trust in him, but she tells him she could sense his regret at leaving her was genuine. Saru is distraught when he realizes his sister and family would still be alive had they known, but Georgiou tells him to avenge them by staying alive. “You are not Terran,” he says, startling Georgiou, who insists she is and that she will mold her home to what she wishes it to be. Georgiou dismisses Saru and checks her wristband bio-scanner, which still displays green.
On the bridge, Airiam reports intercepting a coded message to Lorca’s alias identity from Duggan, who Burnham identifies as one of Lorca’s top lieutenants. The message originated from Risa six hours prior. Georgiou orders Tilly to take Discovery there at high warp, overriding Tilly’s offer to go alone with Burnham in a shuttlecraft. Upon arriving, Gen Rhys reports detecting a single Class A shuttle and no other warp-capable vessels within a hundred light years. Burnham confirms the shuttle’s occupant is Duggan, noting that he has not bothered to properly fix the craft. Duggan powers up, but Georgiou orders the vessel disabled and Duggan kept alive. A single torpedo does the job, prompting Duggan to hail Discovery. Georgiou questions him over the viewscreen, and Duggan reveals that while she was distracted by the Coalition, Lorca rallied the Klingons and Romulans against her. Burnham has him beamed to the brig and orders the Honor Guard to accompany them while promising Georgiou she is not having second thoughts.
With Culber and others looking on, the detained Duggan quips that in person, Georgiou is not so terrifying and lightly tells her not to trust Burnham. “Of course you can… when I want you to,” Burnham says, pulling out a phaser and shooting Duggan in the head. She turns the weapon on Georgiou as Rhys and Airiam enter and kill two of her guards. Burnham reveals she was able to take advantage of Georgiou’s second chance to kill her and save the empire. Georgiou responds that even now Burnham can make a different choice, and that she changed after seeing another way to live. Burnham says she never should have trusted her, and Georgiou responds that she “never did… not like [she] wanted to.” Suddenly, Tilly, Owosekun, Saru, and another Kelpien arrive and start shooting at the traitors. Burnham kills the other Kelpien, Saru kills Culber, Burnham and Georgiou engage in a knife fight; Georgiou gains the upper hand but hesitates to slash Burnham’s throat. Meanwhile, Tilly kills Airiam and Owosekun kills Rhys. Georgiou, having been stabbed with a dagger, withdraws her sword and stabs Burnham through the stomach, whispering “Sorry.” The two lie side by side, dying.
Saru holds the dying Georgiou as Tilly and Owosekun observe. She notes he survived his vahar’ai. She passes out briefly and awakes to find herself back on icy Dannus V with Burnham and Carl. She is disoriented, surprised to learn she experienced some three months in the space of a few moments. Georgiou, however, is still afflicted and in pain. Carl reveals that he is the Guardian of Forever and the wooden door explodes and reconstitutes as a great time-travel vortex.
Aboard the USS Discovery, Paul Stamets and Adira Tal are having difficulty hacking into the KSF Khi’eth‘s systems remotely. Adira posits that the ship was trapped in the Verubin Nebula a hundred and twenty-five years prior, and thus may no longer be intact. Stamets says something must be sending the signal on repeat and pulls more power for their effort. Jett Reno approaches, irked that they have rerouted so much power for their efforts and interrupted her work transitioning the ship from warp plasma conduits to fully polaric conduits.
Adira explains their task and objects to Reno, who is snacking on black licorice, having food in engineering. She replies that it is “not food, it’s candy, it’s practically an accessory.” Cleveland Booker approaches and plugs a glowing device into the console. He says that static in the space–subspace barrier is preventing their connection, and explains that couriers traveling to remote areas use range extenders to amplify weak subspace signals, though Stamets is skeptical since he obtained the device from the Emerald Chain. Discovery can now link its sensors to the Khi’eth to gather data.
On the planet, Burnham asks what a Guardian of Forever is. Carl says he is a space-time portal in hiding because many tried to use him to kill people during the Temporal Wars. He is “nowhere near [his] original coordinates,” and Burnham notes that only the Sphere entity, with over a hundred thousand years of data and access to contemporary Federation databases could have extrapolated his location. Carl says that the still-dying Georgiou was sent back not to be cured, but to be tested to see if she would make different choices, whether her time in the prime universe had changed her. Georgiou says she must have been found to be lacking, since she killed Burnham again, though Carl notes that she tried for peace, saving Saru, which she didn’t have to do. He offers for her to walk through the portal, but she refuses to return to the mirror universe. Carl says he will send her back to a time when the mirror and prime universes were “still aligned” so she will not die. However, he notes, her life will still be difficult. She asks if Burnham can accompany her, but Carl says Michael is right where she needs to be. He tells her to walk through when ready and disappears.
Georgiou tells Burnham she gave her “new life” by bringing her to the prime universe. Burnham says her feelings for Georgiou are for her alone, not because of her prior relationship with the late Captain Philippa Georgiou. The Emperor says she wishes she had said all this earlier and that she regrets not telling Burnham about San, but Burnham urges her to tell the people she will meet upon walking through the portal. Before entering, Georgiou turns back and tells Burnham, “This era is different, more Terran than where you came from. Saru has navigated Discovery admirably. But he’s not the only one who’s suited for the captain’s chair. You have always been far greater than you could imagine, Michael.” Burnham responds that Georgiou is as well, and offers a Vulcan salute, as Georgiou responds with a Terran salute and walks into the portal, which flashes and disappears.
Saru reports to a holographic projection of Admiral Charles Vance about their findings, though Vance is concerned about the use of Emerald Chain technology. Booker replies that he ensured it was safe before installing it on his own ship years earlier. Discovery‘s spore drive makes the ship more attractive to Osyraa, who is running short on dilithium, calling for extra caution, Vance says. He tells Booker to follow Starfleet protocol if he wishes to remain aboard Discovery, but Book replies that Osyraa doesn’t follow any protocols and that having him as a non-Starfleet participant could prove beneficial. Saru receives an alert that Burnham is beaming back to Discovery alone, and Booker leaves to meet her. Vance questions if Saru is distracted by the Kelpien crew of the Khi’eth and orders him to report as soon as he learns anything further. He also offers condolences regarding Georgiou.
In a corridor, Booker tells Burnham he’s sorry for her loss and they embrace. Later, in her quarters, Burnham tells Saru they will not see Georgiou again.
The crew gathers to toast Georgiou, with Dr. Hugh Culber calling her “the most stubborn patient he’s ever had.” Other crewmembers share their ambiguous opinions about about her. Burnham says she was “like a mother, almost; like a sister, almost. I loved her, and hated her, sometimes both at the same time.”