In the salt harvested in apparently quiet village of Gwenrann (Guérande) on Britanny's Atlantic coast, severed hands turn up. Everything points to a serial killer, somehow linked to similar events decades earlier. A task force is formed by St.Nazaire police detective Jérôme Farche, his junior partner Olivier Morel and university forensic experts Ravel and Maxime Nau. They discover curious facts from the first killings, suggesting several suspects, with clues coming even from a mental asylum. Even prosecutor Jérôme Frank plays a dark part.