Franz Fischer is a journalist who also writes novels about casual sex. He sleeps with Anne, the wife of Pierre Bufières, his boss and friend. Unlike the situations he describes in his novels, Franz becomes attached to Anne after making love with her.
Bufières and Anne have an open relationship based on trust, but Bufières is secretly and intensely jealous. He senses that the relationship between Franz and his wife is more than a simple one-night stand.
Bufières and Anne are bound by an agreement - or rather a contract - based on a terrible event in the past that Anne cannot possibly reveal to Franz.
Franz doesn't understand why Anne starts to avoid him, given his charm, his success and above all his casual attitude that should allow their relationship to continue without making too many waves.
Bufières, however, begins to harass Franz insidiously, putting to the test not only the reporter's professionalism, but also the men's mutual trust and friendship.
Inès, an actress friend of Anne, watches Bufières playing cat-and-mouse game with Franz and Anne. Inès knows how dangerous it can be to mix theater and life. And when Alex Darcos, a friend and colleague of Bufières, shows up after five years in Africa, the story of the "contract" comes out and brings the situation to a head...