The day before she is due to leave her psychiatric clinic, a young woman is found dead. Ana's heart has been torn out. Angèle, 29, handles the investigation. It is her first case and she will be working alone. A psychiatric clinic is not the kind of place to send an entire police team. It is not easy to question ‘mad' people and insanity is disturbing and repellent. But not for Angèle. She feels comfortable ‘inside' and finds the inmates engaging, lively and amusing – almost more than the ‘normal' people she meets every day in the outside world. Yet the case is genuinely baffling. Who should she believe? How can she tell the truth from lies? What is the relationship between staff and patients? And the Santis, the psychiatrist couple running the place… Who are they really? Above all, who was Ana? Her diary was found, half-destroyed. Does it hold clues to the mystery?