Opportunity arises for Don and Peggy.Episode titles: 4.1 Public Relations 4.2 Christmas Comes But Once A Year 4.3 The Good News 4.4 The Rejected 4.5 The Chrysanthemum and the Sword 4.6 Waldorf Stories 4.7 The Suitcase 4.8 The Summer Man 4.9 The Beautiful Girls 4.10 Hands and Knees 4.11 Chinese Wall 4.12 Blowing Smoke 4.13 Tomorrowland 10 p.m. Sunday. AMC.