When the U.S.S. Discovery’s crucial mission does not go according to plan, Burnham realizes what must ultimately be done. The crew prepares for the battle of a lifetime as Leland’s Control ships get closer.Burnham opens up a personal log, discussing the incredulous fact that the Discovery crew is in the process of abandoning their ship in order to destroy it. As Discovery contains the one thing in all the galaxy that Control needs, the Sphere data that will allow it to become fully conscious, the sacrifice of Discovery is necessary. Meanwhile, Nhan and Tyler guide the crew to the evacuation points, where they will board the U.S.S. Enterprise, while other members of the crew begin to pack their belongings. On the bridge, Detmer brings the ship up close alongside the Enterprise, and deploys the evacuation corridors that connects the two starships. Around the ship, crew members take one last look at Discovery, recalling better times, before heading over to the Enterprise.



Elsewhere, Burnham stands alone in the science lab, staring at the time crystal. Pike enters and tells her it was time to move to Enterprise. Burnham struggles with the events that led them to this moment; led them to take this drastic action to keep the Sphere's data from being taken by Control. As she and Pike have a philosophical conversation about endings and the roles each of them were meant to play, Saru calls over the intercom to inform Pike that the last of the crew was departing the ship. Pike acknowledges, and makes sure Burnham understood that before he leaves. As she reaches to take the crystal and place it in a containment case, she experiences flashes of the future, seeing the Enterprise under attack at the hands of Control.

On the bridge, Pike and Saru activate the remote detonation sequence for the auto-destruct, after which the Discovery begins to power down. Crossing the evacuation corridor to Enterprise, Saru assures Pike that the ship will be destroyed with the dignity she deserves. As the Enterprise and Discovery crews mingle, Pike, Saru, and Burnham take a turbolift to the Enterprise bridge. As they arrive, Admiral Cornwell vacates the center chair, as Number One welcomes Pike back.



With reports that Leland/Control and his Section 31 armada have increased speed to intercept, Pike orders Number One to take the Enterprise to a safe distance. Pike then orders the auto-destruct sequence to begin. As the computer counts down, the crew watches on, awaiting the inevitable. As time elapses, the computer indicates the auto-destruct has failed. Pike immediately orders a spread of photon torpedoes to be fired at Discovery, but the abandoned ship raises her shields, absorbing the impact. Spock and Burnham deduce that the remaining intelligence of the Sphere is the cause: it would not allow the data to be deleted, and now it has taken over the ship's systems in order to protect itself.



As Number One reports Leland's ships have entered range, Burnham begins seeing the bridge flashing, and suddenly finds herself back aboard Discovery; the bridge on fire. Owosekun reports an undetonated photon torpedo is embedded in Enterprise's primary hull, just as the shields fail. A moment later, Leland/Control enters the bridge and proceeds to gun down the bridge crew, one by one. Burnham painfully reaches for Georgiou's phaser, but Leland steps down on it and kicks it away from her, before drawing his own pistol. Leland lifts her off the ground with one hand and puts the phaser to her head with the other. As he pulls the trigger, Burnham is brought back to the near-present on the Enterprise bridge; just after the failed attempt to activate Discovery's auto-destruct. As Pike orders photon torpedoes, Burnham advises him to stop, indicating it won't work because the Sphere had merged with Discovery and would use her systems to protect the data. With Leland's fleet less than an hour away, Pike asks for options. Burnham and Saru suggest they need to utilize the time crystal to move Discovery into the distant future to insure Control would never get the Sphere data.



In Enterprise's conference room, Pike asks the crew how they could send Discovery to the future before Leland caught up to them. Saru remarks that Section 31 gave them the data on Gabrielle Burnham's suit , and they could attempt to rebuild it. Stamets reminds Pike that the suit was tailored to Gabrielle's DNA, and Burnham adds that as her daughter, she has the closest mitochondrial DNA match, so she volunteers. Number One asks Burnham if she even knows how to fly the suit. Burnham replies she's learned the basics from her mother's logs, and admits there would be some trial and error in opening a wormhole, but if Discovery were on autopilot, it would follow her through. Stamets prepares to have the engineering teams begin work on fabricating a new suit, but Saru reminds them that they also need to find a way to activate the time crystal. Burnham recalls her parents used a stellar-lensing array, but they would need to locate an unstable red giant star. Number One comments that the odds of finding one in any given sector are fairly high, but one close to supernova, Stamets adds, is far less common; it could take hundreds of years to find one. At that moment, Cornwell and Pike are called to the bridge.



As they enter, they find a fifth signal has been detected, and Amin is still getting a lock on its location. With Leland/Control just minutes away, Pike orders red alert, and tells Saru that they will return to Discovery with all essential personnel and use the spore drive to jump them to the signal's location, while Cornwell takes command of Enterprise to join them as quickly as possible. Enterprise goes to warp while Discovery jumps ahead with the spore drive. Arriving first, Burnham reports that the signal has brought them to the planet Xahea, which gets Tilly's attention: She had met the Xahean queen, Me Hani Ika Hali Ka Po, and remarked that they shared a love of engineering. Tilly also remembers that Xahea had a vast natural supply of dilithium, and that Po had developed a method to recrystalize it, but wouldn't tell anyone how she did it, as she didn't trust anyone with that information. Pike comments that this makes her prudent as well as brilliant, and orders Bryce to open a channel to see if Tilly could convince Po to explain why the signal brought them there.



In the transporter room, Tilly waits with a bowl of spumoni ice cream in her hand, commenting on Po's love of sugar, just as she beams aboard. Po enthusiastically embraces Tilly, before she turns her attention to the bowl of ice cream that’s presented to her. She is escorted to the science lab where Burnham explains their plan to use the crystal-powered time suit to travel to the future and take Discovery with her, then come back alone. Po believes she can modify her dilithium incubator to trigger a cascade of energy in the time crystal by combining it with dark energy, which would replicate the power of a supernova. Po and Reno bring up a problem: Using this method of charging the crystal would compromise its structural integrity, causing it to burn out. Burnham would thus be able to take Discovery to the future, but she would not be able to return.



On Discovery's bridge, Tyler is horrified when Burnham and Spock reveal that it would be a one-way trip: To ensure Leland did not get the Sphere's data, Burnham would have to remain in the future – permanently. Burnham would open a wormhole with the suit, and Discovery would follow on autopilot. The job of the combined Discovery and Enterprise crew was to clear a path for Burnham to insure nothing else followed her and Discovery to the future. Saru reports that Enterprise is 57 minutes out, and Control's fleet is ten minutes behind them. Pike reminds the crew that this is what they had trained for, and orders them to come to attention. Burnham fights back tears as she expresses her love for her shipmates, and thanks them for the greatest moments of her life. Pike adds his thanks to the crew, and orders them to get the crystal charged.



In engineering, Po and Tilly continue working on the crystal incubator. Tilly comments she would miss her – only to be surprised when Po says she is staying onboard. Tilly protests, as she is the queen of Xahea. Po calls her world her "sister", and that she would die to protect her; that was the only queen she knew how to be. She reminds Tilly they were a team now, cheerfully adding that they were stuck with her before she carries the incubator away.



As she walks through the corridors, Burnham is astonished to see Sarek and Amanda approaching her. She asks how they knew; Sarek explains that their katras guided them, as they had not been able to reach her through Starfleet; Control had disabled Starfleet's subspace relays, leaving Discovery with ship-to-ship communications only. Sarek realizes that Burnham was truly leaving; she believes it is the only way to keep Control from getting the Sphere data. A tearful Amanda tells her she does not need to go through with it, but Burnham is certain that she does. Amanda expresses pride in her, and in her courage, for what she was about to do. Sarek remarks that every parent's secret wish was that their children made right the mistakes they had made. Amanda expresses their love for her before departing aboard Sarek's ship to return to Vulcan.



As the time for her departure approaches, Burnham prepares for her journey by watching one of her mother's mission logs in her quarters. As she leaves, she runs into Tilly who leads her into the corridor, where much of the senior staff are waiting: Spock, Saru, Stamets, Reno, Owosekun, Detmer, Bryce, Rhys, Nilsson, and Tyler. Speaking for them all, Tilly tells Burnham they planned to stay with her. Burnham protests, saying that she couldn't allow them to do this; Reno replies that they were not asking permission. Burnham insists they have lives and families, people who love them, and that they would never see them again. Saru reminds her that their families accepted the possibility of losing them when they joined Starfleet. When Burnham reminds them she doesn't know what the future holds, Stamets replies no one does – they only had now. Spock makes clear that they were going with her, and that any further argument would be futile. Burnham is trying to find words, but Saru points out that they were out of time – which was a problem, Tilly adds, as the crystal wasn't charging as fast as they had hoped. Reno volunteers to help, and the crew heads to the turbolift. Tyler takes Burnham aside to speak with her in private.



Burnham realizes immediately that Tyler is not going along with her. Tyler believes he needs to remain behind with Section 31, so that nothing like Control could ever rise up again; otherwise, they could end up with the same timeline, no matter where Burnham ended up. Pike calls on the intercom again, reminding her that Enterprise was eleven minutes out; Burnham acknowledges she was on her way. As she makes to head for the bridge, Burnham turns back and tearfully embraces Tyler one last time, before making her way out.



As the Enterprise arrives, Pike addresses the Discovery crew for the last time, telling them that it has been one of the greatest honors of his career to serve as their captain, calling them both exceptional officers and exceptional individuals. He expresses to them all his belief that they would face their destinies with bravery and honor, even those moments that would test the strongest among them. He leaves Saru the conn as Burnham leads them through the wormhole. Number One hails from the Enterprise, informing Pike that Leland/Control's fleet was less than five minutes out. Pike asks Bryce to ensure everyone who planned to leave Discovery had done so, and instructs the remainder of them to go back to work. Burnham calls the crew to attention as Pike leaves.



While both Discovery and Enterprise launch their compliments of small craft, Tilly, Stamets, and Reno continue to work on charging the crystal; at the rate they were going, Stamets warns, the crystal would not be charged before Leland/Control arrived. Reno realizes the cage containing the crystal was interfering with the charge, but without the cage, everyone would experience the effects of the time crystal and witness visions of the future. With no other options and time running out, Reno orders both Tilly and Stamets outside and not to let anyone else in, and assures them she would be fine. As they leave, Reno deactivates the crystal cage, and begins to experience flashes of the future.



On the bridge, Saru asks Bryce to open a ship-wide channel, calling all crew to stations, and ordering red alert. He informs Pike that they were ready to proceed. Pike arrives in the transporter room with Georgiou and Tyler. Pike wishes her luck, and remarks to Tyler that he was glad to have him on their side. Tyler asks if that meant Pike trusted him; when Pike wonders why he asked, Tyler replies that there was something he had to do, and that he would have to leave before the battle began. Detmer communicates to all ships that Leland/Control's fleet has arrived. As Pike steps onto his bridge, Number One reports nine more ships arriving; Burnham can see that the fleet has surrounded them. Aboard Enterprise, Pike orders shields up; on Discovery, Saru tells the crew to prepare for battle.

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