In France during World War I, pretty nurse Marthe (Micheline Presle) waits for her husband, Jacques, while he fights on the front lines. The lonely Marthe begins a tempestuous affair with 17-year-old François (Gérard Philipe), with whom she had a dalliance before marrying Jacques. Jealous François struggles with the fact that Marthe is married, while she tries to prove her devotion to her young, hotheaded lover. Things become even more complex when Marthe becomes pregnant with François' baby.