Montreal police officer Renard is shot in the head and seriously wounded while on duty. A fragment of the bullet remains in his head and cannot be removed. As a result of the accident, he remains partially hearing impaired and has to learn to read lips. Several months later he is back on duty, but his chief is quite wary of him, and reluctantly assigns him the case of a very attractive woman who picks the pockets of men lured by her through newspaper ads. He tries to make contact with the pretty thief by answering an ad she placed, but at the meeting point she addresses another man. That gives Renard the chance to see her at work, and to find her whereabouts. But instead of arresting her, he is intrigued by her actions. Her name is Maria and she steals money to finance a play ("Miss Julia" by August Strindberg) to be staged in a city theater where, twenty years before, her mother was killed before her own eyes while rehearsing the main character of the same play. The girl is obsessed by her memories, and Renard too starts to get to know her deeper while studying her moves. When Renard helps her to flee after robbing a man, his chief asks officer l'Amoureux, his former buddy, to keep an eye on him. The day of the prémiere Maria takes the place of the actress who is going to play the leading role, by drugging her. But she doesn't know that in the revolver on stage the same actress put real bullets. Renard cannot hear her but he sees her lips saying "bullets" and takes action in his hands, but...