Don gets a physical and lies about his drinking and smoking habits. Betty flirts with a rider at the stables. The women in the office speculate about Peggy's promotion, wondering if Don got her pregnant and then promoted her to keep it quiet. Duck tells Roger the company needs younger talent. Don takes Betty to the Savoy Hotel for Valentine's Day. Trudy is upset with the news that Harry Crane's wife is pregnant.
Paul has a party for junior staffers. On Monday the staff listens to a report on an American Airlines crash and Don orders that their Mohawk ads be pulled.
Celebrity comic, Jimmy Barrett causes problems at the Utz Potato Chips shoot. Betty meets Arthur's fiancee, Tara. Harry learns that Ken is making more money than he is.
Peggy's sister has a dinner for the new priest, Father Gill. Roger and his wife talk to their daughter, Mona, about her wedding arrangements. Bobbie Barrett shows up at Don's office with a TV show proposal and seduces him.
Pete and Trudy meet with a fertility specialist. Meanwhile, at the office Joan is excited about her engagement ring. Bobbie invites Don to the celebration of the sale of the TV pilot.
Don and Duck try to make peace. Peggy tries to get into the executive's after hours meetings and Duck deals with a family visit.
Don buys a new car. Meanwhile, Pete, Harry and Ken strategize about how to attract new business. Jane gets fired, but Sterling tells her she can stay. Jimmy tells Betty that he thinks something happened between Bobbie and Don. He later confronts Don about it.
Peggy designs a flier for the church dance, but runs into trouble with the committee. Betty hosts a dinner party for Don's work and then confronts him about his affair with Bobbie which he denies.
Don is still at a hotel. He reads the news that Marilyn Monroe has died. Freddy passes out right before a dress rehearsal and Pete asks Peggy to step in.
Betty goes to visit her father. Trudy and Pete disagree with his mother. Paul's girlfriend tries to get him to prioritize his duties.
Jane spends the night with Roger in a hotel and writes him a poem. Roger meets with a divorce lawyer. Duck wants to be made partner. Pete and Don go to the convention and then drives to Palm Springs with Joy.
Betty punishes Sally for smoking and Sally tells her it's her fault that Don left them. Pete refuses to meet with an adoption agency. Peggy works on the Popsicle campaign. Don, still in Southern California, meets up with Anna. Joan brings her boyfriend to the office. Peggy is excited about her new office.
Betty gets some bad news and the office scrambles to function without Don.