In Paris, the ex-cop Choucas is a private detective that works with a mysterious partner, Tarpon, and the secretary Charlotte. He is presently working in an embezzlement case of an employee of the pharmacist Jude. When the middle-aged Isabelle Pigot hires him to investigate the disappearance of her blind twenty year-old daughter Marthe Pigot that worked at the Drillard Foundation for blinds, the Police Inspector Coccioli seeks Choucas out and asks him to drop the case. But Choucas proceeds with the investigation and schedules an encounter with Isabelle in a square, but she is murdered with a shot on the forehead. Chouca continues to investigate and soon the dirty Chief Inspector Madrier tries to kill Chouca, but he is only wounded and kills the inspector in self-defense. Then two criminals abduct Chouca but he succeeds to escape. He meets his secret partner, the retired Chief of Police Haymann, and Charlotte and they disclose a case of narcotics. Further, Choucas learns that he has been manipulated by Coccioli and other Chiefs of Police.