Anna is a grieving young woman whose fiancé, Frantz, was killed in battle during World War I. When she places flowers on his grave, she notices a young Frenchman, Adrien, also placing flowers on the same grave. Adrien tries to see Frantz’s father, Doktor Hoffmeister, but the doctor refuses to see him, claiming any Frenchman could be the  one who killed his son. Anna gets wind of this and manages to invite Adrien to dinner with the Hoffmeisters. Adrien tells them that he and their son Frantz were good friends when Frantz visited Paris. But when war came, they were on opposite sides. In one encounter Adrien kills a German soldier. Adrien, a pacifist, is wracked with guilt. He comes to Paris to seek redemption. But when lies are revealed, Adrien, Anna, and the Hoffmeisters realize their lives will never be the same.