A psychiatrist discusses mate swapping, warning that it is a game of increasing risk. To illustrate his point he presents several examples of the practice in documentary fashion. First, a young thrill-seeking wife receives a phone call, after which she is apparently kidnaped, taken to an isolated river bank, and ordered to swim naked to a houseboat to spend the night.
In the next scene, Paul and Ellen, an outwardly happy couple, hope to solve their sexual problems with organized extra-marital sex. Once Ellen gets over her initial inhibitions, she becomes an enthusiastic participant in mate-swapping sessions. Another example shows a couple aboard a cabin cruiser for a weekend outing. They encounter difficulty when the clumsy advances of the host repel the guest\\\'s wife, and she has to fight off a rape. In an interview, a wife reveals that she became a prostitute through contacts in the mate-swapping club in order to solve her husband\\\'s financial problems.
Although her husband was sent to prison for living off her earnings, she decides to continue working as a prostitute. In the final scene, Sheila, a childless wife, becomes repulsed by the mate-swapping parties, and one night she throws the guests out and suggests to her husband that a divorce might better satisfy their needs.
