In 1976, the Miller family relocates from a middle-class suburb to Winnetka, Illinois, a more affluent suburb of Chicago. Tom and Trina Decker (Grant Show and Lana Parrilla), the Millers' new neighbors, immediately invite them to join in their open marriage lifestyle. Bruce and Susan Miller (Jack Davenport and Molly Parker) agree to experiment with the Deckers. Roger and Janet Thompson (Josh Hopkins and Miriam Shor), the Millers' neighbors and friends from their old neighborhood, are envious of the Millers' new affluent neighborhood and are appalled when they find out about the sexual lifestyle the Deckers have invited the Millers into.

Meanwhile, the Millers' daughter, Laurie (Shanna Collins) is exploring her own sexual independence, while their son, B.J. (Aaron Howles), learns that a girl has been living in his new room.