Suffering from terrifying hallucinations and alarmingly frequent incidents of amnesia, Anna Heymes, the troubled wife of a French civil servant, finds it increasingly difficult to remember the face of her husband. In the meantime, as the third mutilated body of a Turkish woman emerges from the dark Parisian sewers, the young chief of the investigation, Paul Nerteaux, enlists the help of the dishonoured former detective, Jean-Louis Schiffer. Now, Schiffer's brutal methods, along with his profound experience, are Paul's last hope to shed light on this intricate case. Can they find who is behind the gruesome murders before it's too late?