On the dilithium planet, Saru and Culber continue their efforts to get Su'Kal to overcome his fears of the outside and end the simulation, in order to escape the radiation and prevent another Burn from happening. Adira, who brings the injections against the radiation burns, materializes as a Xahean. Gray too appears, in a Vulcan guise. Osyraa is still in control of the Discovery, and fires on the shield generators of the Federation Headquarters in order to escape. She cuts off life support to the deck where Tilly and her team have begun to retake the ship. The Discovery eventually breaks through the shields, but a fleet from Ni'Var arrives and prepares to attack. On Burnham's request, in order to avoid further bloodshed, Vance allows the Discovery and the Viridian to withdraw. In sickbay, Aurellio uses a truth serum on Booker to find out the way to the dilithium planet. When this effort fails, Osyraa orders Zareh to torture him. Burnham asks to speak with Book, erects a forcefield around his biobed and escapes with him. She gives Tilly a cue about sabotaging the warp nacelles, in order to stop the ship and regain control. On the dilithium planet, Saru reveals to Su'Kal that he a is Kelpien too. Culber, with the support of Adira, muses that Su'Kal is a polyploid and formed a genetic connection to the dilithium. When he screamed, the sound propagated through subspace at the resonance frequency of dilithium and thereby caused the Burn. On the Discovery, Burnham proceeds to the computer core to reboot the system, while Booker is stuck in a turbolift with Zareh. With little oxygen left on their deck, only Owosekun makes it to the nacelle and successfully disrupts its connection. The ship drops out of warp. Burnham arrives in the computer core where she faces and eventually kills Osyraa. She reboots the computer and beams off the regulators. But the ship is inside the Viridian by now. Burnham suggests to eject the warp core to destroy the Viridian, while Book connects with the spore drive to preform a jump. The Viridian gets obliterated in a huge explosion. On the dilithium planet, Su'Kal enters the room that frightens him and ends the simulation. Gray disappears, but with the promise that the crew would work on a way to make him permanently visible. The death of Su'Kal's mother is replayed, which terrified the boy and led to the Burn. The Discovery arrives and beams up the away team and Su'Kal. The Emerald Chain fractures after Osyraa's death, whereas more worlds consider to rejoin the Federation. The dilithium planet is going to be mined, helping the worlds to reconnect. While Saru stays on Kaminar with Su'Kal for the time being, Michael Burnham becomes the new captain of the Discovery.

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