At the Citadel of Besançon, Anna reads while Lou, her 10-year-old daughter, goes to see the animals. Time passes and Lou does not return. Worried, Anna goes looking for her when she receives a call from her daughter. But it is not Lou on the phone, but a man who tells him that he has just kidnapped his daughter. Anna thinks of a bad joke, but when she realises that her daughter is under a face mask and has an hour’s supply of oxygen, it is horror. Anna must stay on the line and not talk to anyone if she wants to see her alive again. Forced to obey this sadistic predator, she will have to perform increasingly violent acts until she kills a man. Locked in a strangely deserted citadel, Anna will do everything to extricate herself from this nightmare. Will she get there?
