As young French couple Gilles and Marion officially separate, we see, in reverse order, the milestone moments in their relationship: Gilles revealing his unfaithfulness at a tense dinner party; Marion giving birth to their premature son while Gilles is elsewhere; Gilles and Marion's joyous wedding; and, finally, the fateful moment when they meet as acquaintances at an Italian beach resort, and their love affair begins.

Paris, 1960s. Momo, a resolute and independent Jewish teenager who lives with his father, a sullen and depressed man, in a working-class neighborhood, develops a close friendship with Monsieur Ibrahim, an elderly Muslim who owns a small grocery store.