After being raised as a Vulcan by Sarek, and becoming the first human to attend and graduate the Vulcan Learning Center and the Vulcan Science Academy, Michael Burnham is entrusted to Philippa Georgiou, captain of the USS Shenzhou, by Sarek. Seven years later, Burnham is the first officer of the Shenzhou, and has just disobeyed and attacked Georgiou in an attempt to fire, unprovoked, on a Klingon vessel, hoping to avoid an inevitable war. The Klingon outcast Voq, on behalf of his leader T'Kuvma, has just started a beacon that attracts 24 new Klingon vessels to the system, as Georgiou has Burnham arrested and imprisoned for mutiny.
The leaders of the 24 great houses question T'Kuvma's use of the beacon, which was prophesied to be used to unite the Klingon Empire once again. T'Kuvma is of a disgraced house, and the House of Kor leader Kol refuses to listen to T'Kuvma, especially given his acceptance of outcasts like Voq. T'Kuvma pleads with the other leaders to join him in fighting the United Federation of Planets, who he says intends to destroy their species' individuality. He predicts that reinforcements for the Shenzhou will soon arrive, and that they will announce that they "come in peace", and when these come to pass, the other leaders agree to fight.
The Starfleet ships take heavy fire, and the Shenzhou is almost destroyed, but is saved by the arrival of Admiral Brett Anderson and the USS Europa. T'Kuvma agrees to a ceasefire with Anderson, but then sends a large vessel, hidden with cloaking technology, to ram and destroy the Europa. The latter self-destructs, taking the large vessel with it. T'Kuvma proclaims himself Kahless, the ancient uniter, reborn, and allows the rest of Starfleet to escape as messengers of this. He sends the other Klingon leaders back to Qo'nos while he tends to their dead. In the damaged Shenzhou, Burnham escapes the brig after telepathic encouragement from Sarek, and convinces Georgiou to take T'Kuvma hostage.
Using an explosive sent to T'Kuvma's ship with a Klingon corpse as a distraction, Burnham and Georgiou board the ship and attack. Burnham fights off Voq, but Geogriou is killed by T'Kuvma. Burnham fatally shoots T'Kuvma, before being transported back to the Shenzhou. Voq promises the dying T'Kuvma that he will be remembered. Burnham is later sentenced to life in prison by Starfleet for her mutiny.