Tony "le Stéphanois," an aging gangster recently released from prison, is down on his luck. Approached by his close friend Jo and their associate Mario, Tony is drawn into planning a high-stakes heist. The target is a high-end Parisian jewelry store, Mappin & Webb Ltd., known for its impregnable security system. Despite initial reluctance, Tony's desperation for money and a desire for one last big score lead him to join the scheme. The trio, along with an expert safecracker named César, meticulously strategize their approach, making preparations that involve elaborate technical expertise and careful planning.

On the appointed night, the gang carries out their meticulously rehearsed heist, successfully bypassing the sophisticated security measures to steal a fortune in diamonds. However, their victory is short-lived as tensions rise, and unforeseen complications jeopardize their success. As their carefully constructed plan begins to unravel, trust is put to the test and alliances are strained.