Back nine months late, Discovery learns the Klingons are winning the war, and Starfleet turns to the mirror Georgiou to lead a strike on Qo'noS.
Sarek and Admiral Cornwell come aboard and explain that the Klingon houses are now competing with one another to destroy the Federation, and that Starbase 1 has fallen. Tyler, his human personality restored by L'Rell's procedure but still holding Voq's memories, struggles to find a place, and Burnham cannot forgive him. Stamets terraforms a moon to grow a new supply of spores.
Needing a commander willing to win at any cost, Starfleet places the mirror Georgiou in command of Discovery, posing as the original captain, to lead an attack on the Klingon homeworld Qo'noS. Lisa Randolph wrote the episode and David Solomon directed.