A boy, Christian, sees his father murder his mistress in a mirror-lined room. Years later, he returns to the family home with Helene, his fiancée, and another married couple who are close friends, Paul (his lawyer) and Brigitte. Christian is haunted by the idea that his father - who supposedly committed suicide by throwing himself from a cliff - may still be alive. Strange occurrences, such as finding his father's still smoking pipe, lead him to suspect that Paul is trying to gain his inheritance, however...