By chance, Marc Lemaire meets his ex-babysitter Claudine Grenier. When they last saw one another thirty years earlier, a fire in the Lemaires' house killed Marc's mother. He'd like to talk to Claudine, but she's reluctant.

Although Claudine's children and husband appreciate the help provided by Marc, an estate agent, Claudine's parents and sister and Marc's father and wife are unhappy. Stéphanie learns more about the boy pictured in a photo from her mother's youth.

While Marc keeps coming up with reasons to see Claudine, disturbing revelations concerning the past life of Jacques, Marc's father, shed new light on the current situation.

Stéphanie spots a link between the fire, Jean Forget and certain past events. Meanwhile Claudine and Marc's lives are turned upside down.

Jacques' presence and that of a mystery guest causes a commotion at a party organised for Claudine. Although some details from the past are now clearer, the mystery remains unsolved.

Mylène becomes interested in Jean Forget's story, seeing it as inspiration for her novel. Stéphanie is suspicious of Jacques Lemaire, believing him to responsible for Forget's suicide. As Claudine ends her affair with Marc, terrible events befall him.