Alcide Chanal is recording a message of congratulations on his phonograph to send to his sister ahead of her wedding, but is interrupted by a string of guests - his friend Hubertin, and the politician Coustillou - as well as his wife Francine who has has finally worked up the courage to tell her husband that she has been unfaithful to him. She has a lover, who loves her, makes her feel valued beyond the trappings of being a mere wife. Sadly for her, Alcide does not believe her. It is nonetheless true: and to compound this cuckolding so close to home, Alcide unwittingly leases his ground floor apartment in his building to his rival, an ex-schoolmate named Massenay. When Massenay and Francine's cooing is captured by the phonograph, Alcide has proof positive that his wife has been unfaithful, though not who his rival is. Delighted by this dramatic turn of events, he pursues each of his suspects manfully, intending to extract his justice as though it were a rare and juicy pleasure.