The 1970s... The married couple Susan and Bruce Miller move with their children to a prestigious Chicago suburb, anticipating a new, ideal life. For them, that means backyard picnics and children playing nearby. However, after meeting their new neighbors Tom and Trina Decker, the Millers realize that alongside traditional sexual relationships there are also open marriages, in which the choice of a sexual partner and group sex are perceived as an integral part of family life. The Millers' previous neighbors, Janet and Roger Thompson, completely do not understand and do not accept such sexual freedom.