Aimée's childhood friend, Laure, is a policewoman. Her partner, Jacques, has set up a meeting in Montmartre with an informer. When Laure goes along as backup, Jacques is lured to a rooftop where he is shot to death. Laure's gun has been fired, there is gunpowder residue is on her hands, so she is charged with her partner's murder. As the police close ranks against the alleged cop killer, Aimée is determined to clear Laure's name. In doing so, she encounters Separatists terrorists, Montmartre prostitutes, a Surrealist painter's stepdaughter, and crooked Corsican bar owner.