Fleeing the June 1940 arrival of Hitler's army in Paris, a young war widow and her two children are rescued from dive-bombing German fighters by a cocky, reckless teenager. He finds them refuge in an abandoned house, but despite the fact that the family quickly comes to be depending much on his cunning and survival abilities, their cohabitation proves uneasy.
Martin, the illegitimate son of an industrialist and a hairdresser, was sent to live with his wealthy father in the countryside as a young boy. Alice is a musician living with Martin's half-brother in Paris. When Martin shows up at Alice's door after fleeing his father's home under troubled circumstances, their lives become intertwined.
In the middle of the night, someone brings Ivan's body home to his wife and his young son. Flashbacks reveal the relationships among Ivan and his brother Alex, a cop with a cleanliness fetish; siblings Juliette and Jimmy, Ivan's partners in a seedy nightclub; the love triangle of Alex, Juliette, and Marie, a professor of philosophy; and of Alex and his nephew, Ivan's dour, stoic son. Ivan's death changes every relationship.
As the Algerian War draws to a close, a teenager with a girlfriend starts feeling homosexual urges for two of his classmates: a country boy, and a French-Algerian intellectual.