It is the winter of 1937, and Aimé Louzeau lives with his mother and their servant. One day, he goes to the Quai des Orfèvres, the police prefecture of Paris, to speak with the vice squad. He currently works in the Criminal Investigation department, but crimes of passion and back alley stabbings really aren't his thing, so he requests a transfer from Chief Inspector Séverin. The atmosphere immediately darkens, as Louzeau is thrown straight into the interrogation of a pimp called Guapito and his prostitute.