The Forbidden Photos of a Lady Above Suspicion (1970)

A triangle of friendship, love, sex, and, perhaps, murder. Minou is newly married to Peter, a businessman in debt as he works to bring a new product to market. They met through Dominique, sexually voracious, Minou's best friend, and Peter's former (and possibly still) lover. A stranger accosts Minou one night on the beach while Peter is away. He tells her that Peter has murdered a business associate and blackmails her into sleeping with him. He compounds the blackmail with photos taken of their tryst. To Minou's surprise, this same stranger is in a pornographic photo Dominique has imported from Denmark. Is this all a game, and if so, who's behind it?