Jaded cabaret singer Mademoiselle Amy Jolly (Dietrich) falls for Tom Brown (Cooper), a devil-may-care private in the French Foreign Legion. After Tom overhears the wealthy man-of-the-world Monsieur La Bessier (Adolphe Enjoy) propose to Amy, he accepts a dangerous assignment, convinced that he cannot can give the beautiful chanteuse the life she wants. All proves fair in love and war, however, and Amy must decide which man she truly loves.