Bernard and Mathilde fall madly in love, before going through a turbulent break-up. Seven years later, fate brings them back together when Mathilde — who has recently married Philippe — moves into the house next door to the one where Bernard, his wife Arlette and their young son Thomas live. Madame Jouve, a witness to and confidante of the two former lovers, sees them seal a non-aggression pact. Who will be the first to break it?