Season synopsis
Contains spoilers for this season and earlier seasons.
Don starts the final season on leave, secretly writing through Freddy Rumsen. Returning to Sterling Cooper & Partners under restrictive conditions, he faces Lou Avery’s authority and Jim Cutler’s efforts to remove him. His marriage to Megan ends. Bert Cooper dies after watching the Moon landing, and Peggy wins Burger Chef with Don’s support. Roger negotiates the sale of a controlling share to McCann Erickson, preserving the agency temporarily as a subsidiary. In the season’s second half, McCann absorbs it completely, ending the partners’ independence.
Joan faces harassment at McCann and accepts a reduced payout to leave. Peggy joins its creative staff, but Don walks out of a meeting and drives west, looking for waitress Diana before continuing across the country. After confronting his wartime past among Oklahoma veterans, he gives his car to a young hustler. Pete reconciles with Trudy and takes a Learjet job in Wichita. Betty is diagnosed with terminal lung cancer and refuses treatment, giving Sally instructions for her burial.
Don asks to take his sons after Betty dies, but she wants them raised by her brother and his wife; Sally returns home to care for them. Joan starts a film production company while Peggy stays at McCann and acknowledges her love for Stan. Roger plans to marry Marie. Stephanie takes Don to a California retreat, then leaves him there. He calls Peggy in despair before joining a group session and embracing Leonard, who describes feeling unseen. The series closes with Don smiling during meditation, followed by the 1971 Coca-Cola commercial, leaving the connection for viewers to interpret.