In France in 1942, a young Jewish woman named Léna is interned by the Vichy authorities and faces the risk of deportation to Nazi Germany. Michel, one of the guards, offers to save her by marrying her. They escape on foot over the Alps to Italy. After the war, they settle in Lyon, where Michel opens a garage and Léna has two daughters with him. At a school event, she meets another mother, Madeleine, who is married with one son. The two women become close friends, and their husbands also get along, although both men secretly feel jealous of the bond their wives share.
Madeleine has a brief affair with her former art teacher, for which Léna lends her flat. Unfortunately, Michel comes home at lunchtime and discovers the guilty couple. This turns him against Madeleine and strains Léna's friendship with her. The two women had been planning to open a dress shop, and Michel offers to finance it on the condition that Madeleine is excluded, as she has gone off to Paris. Taking a night train to visit her, Léna has a sexual encounter with a soldier, her first experience apart from Michel, which she finds very enjoyable. In Paris, the two women dance, get drunk in a nightclub, and end up in bed together.
However, Léna fails to realise the fragility of Madeleine, who is eventually placed in a mental hospital and later released to the care of her parents. When Léna visits her, she takes Madeleine out to show her the new dress shop. Unfortunately, Michel drops by and upon seeing Madeleine there, he smashes the place up. Léna takes Madeleine and their children away to a rented house by the sea, where Michel tries to reconcile with her but without success. The end caption reveals that Léna never sees her husband again, and Madeleine dies two years later.
