The year is 1766. The population of Gevaudan, a wild and scenic region in Southern France, has for some time been terrorized by a terrible monster. More than a hundred people have fallen victim to what they believe is a giant wolf. When the panic starts to spread across the region, sending King Louis XV of his ablest soldiers to kill the beast. This, however, fails. The king commands when the eminent scientist Grégoire de Fronsac – together with his friend Mani, an Indian, he got to know in North America – go to Gevaudan to try to solve the mystery of the invisible, the ruthless enemy.