After five years in prison, Tony le Stéphanois meets his dearest friends Jo and the Italian Mario Ferrati, who invite Tony to steal a couple of jewels from the show-window of the famous Mappin and Webb Ltd, but he declines. Tony finds his former girlfriend Mado, who became the lover of Louis Grutter, gangster owner of the L' Âge d' Or nightclub, and he humiliates and beats her for being unfaithful. Then he calls Jo and Mario and proposes a burglary of the safe of the jewelry. They invite the Italian specialist in safes and elegant wolf Cesar to join their team and they plot a perfect heist. They are successful in their plan, but the Don Juan Cesar errs by giving a valuable ring to his mistress.