When Béatrice (Estella Blain) decides to spend an evening with a group of wealthy playboys, her working class fiancé, Pierre (Robert Hossein), follows her and exposes a gang of organized criminals. Intercepted by henchmen, Pierre is threatened, beaten, and framed for murder. But he refuses to give up, and remains determined to infiltrate the criminal stronghold, liberate Béatrice from the sex traffickers, and clear himself of murder.