The Marseille police commander Michel de Palma should really be recovering from his injuries sustained in his last case. However, Ingrid Steinert, the wife of the billionaire German industrialist William Steinert, needs his help: her husband has been missing for several days. Although initially not particularly interested, the case piques de Palma's curiosity when Steinert's body is found in the muddy swamps of the Camargue. The police believe they know the solution quickly: drowned, an accident. Then events take a turn as more and more bodies appear, all mutilated in a bestial manner. Is the Tarasque, the monster from the swamps, more than just a myth?.