During the French Revolution, Marquis d'Apcher writes his memoirs in his castle. He recounts to 1764, when a mysterious beast terrorized the province of Gévaudan. Grégoire de Fronsac, a knight and the royal naturalist of King Louis XV of France, and his Iroquois companion Mani, arrive to capture the beast. Fronsac grows to romance Marianne de Morangias, the daughter of a local count, whose brother, Jean-François, was also an avid hunter and a world traveller. Fronsac is also intrigued by Sylvia, an Italian courtesan at the local brothel.