Without seeming to touch it, journalist Trupeau is interested in the doings of Mireille, a jewelry store saleswoman. A certain Jojo is hanging around the young girl, and not for the right reasons, but to pull off a "heist". Although one of his men betrays him and has to be shot, Jojo succeeds. The police investigate, question and pursue Mireille. Exasperated and disillusioned, the pretty salesgirl shoots Jojo. Fortunately, the journalist is there to prove that she's as white as an ermine. And the ch timents rain down on the culprits.

Jojo prépare le casse d'une bijouterie. Pour parvenir à ses fins, il séduit la vendeuse, qui se retrouve compromise après le hold-up.