While she was jogging Lisa Campion , the daughter of the retired police officer Fabio Campion , discovered the frozen corpse of Julien , a child who disappeared 20 years ago.The police officer Simon Beauregard is then sent to Roches Noires , a village of the Tarentaise Valley, for the criminal investigation.

Paris, the 1980s. Three students decide to celebrate their graduation with a visit of the Paris catacombs. But something, someone, is hunting them. Trapped deep underground, the group needs to get out before it's too late...