It's 1765 and a mysterious beast is killing scores of women and children in the Gevaudan region of France. Accordingly, and not satisfied with the unfruitful results produced by Capitaine Duhamel (ERIC PRAT) in finding and killing the creature, the King sends scientist Grégoire de Fronsac (SAMUEL LE BIHAN) and his taciturn Iroquois companion Mani (MARK DACASCOS) there to investigate the killings.
After questioning a recent survivor of such an attack, the two arrive at the estate of the Marquis d'Apcher (HANS MEYER) where they two meet his grandson, Thomas (JÉRÉMIE RÉNIER), who will assist them, as well as Jean-François de Morangias (VINCENT CASSEL), a one-armed aristocrat, and his ravishing sister Marianne (EMILIE DEQUENNE). Instantly attracted to her, Fronsac proves that even nobility can be fooled by a clever prank, a point that doesn't sit well with most of them.
After an unsuccessful hunt rounds up plenty of innocent wolves but no such beast, the men visit the local brothel where Fronsac meets the mysterious and alluring Sylvia (MONICA BELLUCCI), a seer of sorts who fulfills his psychic and physical needs.
As time passes and winter arrives with more killings, the King relieves Duhamel of his command and sends in his own lieutenant, Beauterne (JOHAN LEYSEN), to resolve the matter. Reduced to just a witness, Fronsac is forced into going along with the officer's solution to the beastly killings. Yet, he knows it won't work, and thus sets out with Mani and Thomas to find the deadly creature. With the local priest Henri Sardis (JEAN-FRANÇOIS STÉVENIN) believing the two visitors to be up to no good, the trio ends up uncovering more than they bargained for as they discover the truth behind the attacks.