Xavier Durmont young deputy newly elected, is charged by a representative of the Court of Auditors to investigate a dubious case of waste disposal involving a minister. He becomes then the target of slander orchestrated by the agency of a mysterious Armand.
Prosecutor Vadim, who has an uneasy relationship with his glamorous wife Chanéac, vanishes at the time a psycho is offing club girls to the strains of the "Tu es si jolie ce soir" song.
