The body of a young woman, Béatrice Dumontier, is found in a thicket in the woods of Meudon. PJ Commissioner Rossi is investigating the murder. One of his former assistants, Gille Cauvin, who has become a private detective, is also working on the case. Traces of Béatrice leads them to the Black Angel, a cabaret which serves as a facade for several illegal activities: blackmail, drug trafficking, trafficking of white women, and financial espionage.