After the nanny of a police captain's son dies from a lethal drug, the captain sends a chemist undercover to infiltrate the Marseille drug ring led by a charismatic figure.

The baby sitter of police captain Max Vernet's son suddenly dies; victim of a new and dreadful synthetic drug. Vernet has the idea to have someone infiltrate the network that operates from Marseille, with the charismatic Jesus at its head. He chooses Aurélie, a chemist and single mother. The lady must offer her services under the pretext of improving the product.—Guy Bellinger