Out of prison after a five-year stretch, jewel thief Tony turns down a quick job his friend Jo offers him, until he discovers that his old girlfriend Mado has become the lover of local gangster Pierre Grutter during Tony's absence. Expanding a minor smash-and-grab into a full-scale jewel heist, Tony and his crew appear to get away clean, but their actions after the job is completed threaten the lives of everyone involved.

Léo Fardier is a police inspector who goes to prison undercover as a convict. He shares a cell with Mariani, a Corsican mafioso, whose trust he earns. The day Léo leaves prison, the criminal entrusts him with a letter to deliver to his estranged wife. He finds her, and she falls under his spell. The problem is that he, too, has fallen in love with her.