Les couples du Bois de Boulogne (1974)

In order to receive their part of an inheritance from an uncle, Barbara and Bernard, a couple about to divorce must find the other beneficiary, Jean-Pierre, the illegitimate son of the uncle. As they search for him, they arrive at Boulogne, which they will find is used by rich people as a place to be sexually free in total privacy. There, they will be led by other couples to fulfill their most daring fantasies.