Rich industrialist Jacques Decret learns his wife Gloria is having an affair with a young actor. For revenge, he bombards her with anonymous letters, convincing her that her lover is the culprit while Gloria desperately seeks a way out.
Young, handsome, dashing but cynical, Octave Mouret arrives in Paris, determined to conquer the belles of the capital.
Stéphane Blanchon lives a quiet life in Switzerland with his wife, Christine, until a young American boarder named Belle, who was living with them, is found murdered. Despite Stéphane's innocence, the evidence points to him, and he learns that Belle harbored romantic feelings for him. Suspicions mount against him; even Christine thinks he is the culprit. Stéphane's sanity begins to crumble, and he lashes out in unprecedented ways.
