In 18th century France, a mysterious beast terrorizes the province of Gévaudan, brutally killing women and children. With the king fearing for the safety of his kingdom and the public outcry for a solution growing louder, knight and royal naturalist Gregoire de Fronsac, along with his Iroquois companion, Mani, are sent to capture the creature. Upon arrival, they delve into the investigation, utilizing their unique skills and scientific methods. Fronsac is a man of enlightenment, skeptical of superstitious explanations and determined to find a rational cause for the beast's savagery. Mani, with his deep connection to nature and exceptional tracking abilities, complements Fronsac's analytical approach.

As they probe deeper into the murky circumstances surrounding the attacks, they encounter a tangled web of intrigue. The province's secretive power structure, resistance to their investigation, and ominous hints of something sinister at play only complicate their quest for the truth. During their stay, Fronsac becomes enamored with Marianne de Morangias, a beautiful aristocrat, adding a personal stake to his mission. They soon realize that the beast is not the only threat in Gévaudan, and their battle against ignorance and fear might be just as dangerous as confronting the creature itself. With each step closer to unveiling the mystery, they are drawn into a world of political conspiracies, ancient rituals, and an enigmatic woman whose role in the events is unclear.