The full plot of Creed 3 follows Donnie's reunion with Dame, a title fight that goes badly wrong, and a final bout at Dodger Stadium that settles what the two men owe each other.
As teenagers in Los Angeles, Donnie and Dame are close, and Dame dreams of becoming a world champion. After a fight, an incident involving a man named Leon gets Dame sent to prison, while Donnie leaves and cuts contact. Years later Donnie has retired and focuses on his family and on the Delphi Boxing Academy, where he works with Tony "Little Duke" Evers and manages Chavez.
Dame comes back from prison and Donnie lets him spar with Chavez, though the gym staff dislike his rough style. Dame asks for a title shot and Donnie says no. Then Chavez's scheduled opponent, Viktor Drago, is attacked, and Donnie puts Dame in as the replacement. Dame wins the heavyweight title by knockout with dirty tactics and badly hurts Chavez's injured shoulder.
Donnie's adoptive mother Mary-Anne then shows him letters Dame wrote from prison, and Donnie realizes Dame manipulated him into the fight. They clash on a beach and Donnie is hurt, and Dame publicly mocks him as a fraud. Mary-Anne dies after another stroke, and Donnie tells Bianca the true story of the night of Dame's arrest, which involved an abusive caregiver and a gun.
Pushed by Bianca, Donnie comes out of retirement, trains with Duke and a recovered Viktor Drago, and agrees to face Dame at Dodger Stadium. In the last round Donnie is knocked down but beats the count and knocks Dame out to win back the title. The two men make peace, and Donnie shadowboxes with Amara in the empty ring.