Jean-Louis, a solitary and serious engineer, has taken a job in Clermont-Ferrand where he knows nobody. Attending a Catholic church, he sees a young blonde woman and without knowing anything about her is convinced that she will become his wife. In the street he sees Vidal, an old Marxism friend now a university lecturer, who invites him to a concert the next evening. After the event, Vidal tells Jean-Louis he is going to see a friend and persuades him to come as well.