Late on a lonely night made of life's cynical twists, prosecutor François Marcorelle meets a Polish girl in a restaurant in Chambery and follows her up to her room. There, a series of bizarre events lead him to kill a man. Or so he thinks. His friend Georges, a doctor, is convinced this is only one of his chronic nightmares. But this time, Marcorelle is sure, it's all too real. There, lurking in the darkness of a movie theater one afternoon, is the proof.