After five years in prison, Tony le Stéphanois meets his dearest friends Jo and the Italian Mario Ferrati and they invite Tony to steal a couple of jewels from the show-window of the famous jewelry Mappin & Webb Ltd, but he declines. Tony finds his former girlfriend Mado, who became the lover of the gangster owner of the night-club L' Âge d' Or Louis Grutter, and he humiliates her, beating on her back 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 makes things go wrong when he gives a valuable ring to his mistress.