Bernard Codre, a ship’s engineer, lives in a village near Grenoble. He has never told his wife, Arlette, about a long affair he had with a young artist named Mathilde before his marriage, and now he is shocked to learn that Mathilde and her husband, Philippe Beauchard, who is much older than she is, have rented a neighboring house. He refuses to attend the reception Arletta is throwing in honor of the new neighbors, but the next day he meets Mathilde quite by chance in a supermarket. The relationship seems to be quite friendly, but suddenly Bernard, giving in to a momentary impulse, ardently embraces Mathilde, and she even faints. The social life of the village revolves around the tennis club of Madame Juve. There Mathilde meets the publisher Roland Duguet and resumes her once interrupted work as a children’s book illustrator. Bernard and Mathilde begin to meet regularly, for which Bernard rents a hotel room in Grenoble. However, Mathilde refuses his offer to start their life together again. They return home and stop the car for a final explanation. And in fact, all of Bernard’s subsequent attempts to revitalize their relationship are fruitless. Bernard is desperate. During one of the receptions organized this time by the Bouchard couple, he loses his temper and publicly beats Mathilde. Time passes. Arlette, pregnant with her second child, and Philip, who has been caring for the distraught Mathilde during a cruise in North Africa, have come to terms with what has happened. Mathilde and Bernard seemed remorseful. But one day at the same tennis club, Mathilde, signing copies of a new book she had just designed, became ill. In the hospital, she collapsed and refused anyone’s support, even the sympathy of Bernard, who visited her at Philip’s request. She finally recovers, and the Bouchard couple move to a new apartment. One night Bernard is awakened by a noise in the neighboring house. Entering the house, abandoned by the Beauchards, he finds Mathilde there.