While working in Africa, young police officer Grégoire Morvan managed to track down and arrest the serial killer known as the Nail Man. Many years passed: Grégoire started a family, returned to France, rose to high ranks—yet his son Hervan also became a police officer. But the horror that seemed to be gone forever returns. An investigation into what at first looks like a random death leads Hervan to the conclusion that someone is committing murders again—using the templates of the Nail Man.