"Francois Truffaut's vibrant and adult adaptation of Henri-Pierre Roche's 1953 novel is one of the high-water marks in the French New Wave movement of the early 60s. The film examines the failure of a menage-a-trois between three people who love each other. The story begins in pre-World War I France, where Jules (Oskar Werner), a shy and studious German, befriends Jim (Henri Serre), an outgoing Frenchman. While looking at slides of Greek sculpture, a portrait of a woman with an enigmatic smile grabs the attention of the two friends. They both vow that if they ever come across such a woman in real life, they will marry her at once. Their ideal becomes reality in the corporal form of Catherine (Jeanne Moreau). They are both taken with her, but when Jules asks Jim if he could have Catherine for himself, Jim reluctantly agrees, and they are married. World War I breaks out and the three friends are separated on opposite sides of the battlefield, but they survive the conflagration. After the war, Jim travels to Germany to visit his old friend with his five-year-old daughter Sabine (Sabine Haudepin) in tow. Jim discovers that Catherine has been unhappy being tied-down as a wife and is having affairs. Jules is aware of Catherine's infidelity but still insists on staying with her. Jim comes up with what he thinks is the perfect solution: he will marry Catherine and she can stay within the tight circle of Jules and himself. Catherine agrees, to dire consequences."