Season synopsis
Contains spoilers for this season and earlier seasons.
Sterling Cooper resumes with Don and Betty trying to restore their marriage, though both know the earlier betrayals have not disappeared. Peggy returns to copywriting after an absence the office misreads; she conceals having given up a child. Duck Phillips pushes to modernize the agency and replace older staff, setting up a contest between his plans and Don's instincts. Pete and Trudy remain unhappy about not having a child, while Roger leaves Mona for Don's secretary Jane.
During Don's affair with Bobbie Barrett, a drunken car crash forces him to call Peggy, who bails them out and helps conceal it. Jimmy Barrett later tells Betty about the affair, and she makes Don leave home. Don disappears during a California work trip and visits Anna Draper, the widow of the man whose identity he took. Meanwhile, Peggy gains responsibilities after Freddy Rumsen is dismissed. Greg rapes Joan in Don's office, but she remains engaged to him. Pete resists Trudy's adoption plans, prompting his father-in-law to threaten the Clearasil account.
As the Cuban Missile Crisis makes the threat of nuclear war immediate, Betty learns she is pregnant as Don returns from California. She briefly seeks independence through a night out and a stranger, then asks Don to return home and tells him about the baby. Peggy tells Pete directly that she had his child and gave the baby up, closing the possibility that they might resume their earlier romance. Don returns to Sterling Cooper, rejects Duck's bid to control him by pointing out that he has no contract, and Duck loses the position he had expected to gain from the sale to Putnam, Powell & Lowe.