Le pacte des loups
The film begins during the French Revolution, with the aged Marquis d'Apcher as the narrator, writing his memoirs in a castle, while the voices of a mob can be heard from outside. The film flashes back to 1764, when a mysterious beast terrorized the province of Gévaudan and nearby lands.
Grégoire de Fronsac, a knight and the royal naturalist of King Louis XV of France, and his Iroquois companion Mani, arrive in Gévaudan to capture the beast. Upon arrival, they rescue Jean Chastel, an aged healer, and his daughter La Bavarde from an attack by soldiers. The young and enlightened Thomas—Marquis d'Apcher—later befriends the two outsiders.
Fronsac is initially skeptical about the beast's existence, since survivors describe it as much larger than any wolf he has ever seen. However, by studying the bite size on a victim of the beast, he deduces that it must weigh roughly 500 lb (227 kg). Captain Duhamel, an army officer leading the hunt for the beast, has killed dozens of ordinary wolves, but has not come close to the actual killer. While staying in Gévaudan, Fronsac romances Marianne de Morangias, the daughter of a local count, whose brother, Jean-François, was also an avid hunter and a world traveler, before losing one arm to a lion in Africa. Fronsac is also intrigued by Sylvia, an Italian courtesan at the local brothel.
While investigating another victim, Fronsac finds a fang made of steel, which increases his doubts of the beast's existence. Another witness swears that the beast is controlled by a human master. Fronsac studies the patterns of the attacks and victims, trying to find a common thread and reveal a murderer. As the investigation proves to be unfruitful, the king's weapons master, Lord de Beauterne, arrives to put an end to the beast. However, instead of doing so, Beauterne kills an ordinary wolf and tells Fronsac to alter the corpse so it resembles the monster accordingly. Fronsac hesitantly does so, and the bogus wolf is sent back to Paris, where it is put on display, much to the pleasure of the king and the French aristocracy.
In Paris, the king's advisor shows Fronsac a copy of a book titled L'Édifiante (French for "The Edifying"). Within the book are treasonous theories, such as that the beast has come to punish the King of France for his indulgence of the philosophers, and that the modern embrace of science over religion is heresy. Fronsac realizes that the beast is actually an instrument of a secret society: The Brotherhood of the Wolf, which is working to undermine public confidence in the king and ultimately take over the country. Fronsac is told that "officially" the beast is dead, warned to stay silent, and bribed with an appointment to travel to Senegal. Back in Gévaudan, the attacks by the real beast continue. Ignoring his orders, Fronsac returns to Gévaudan, determined to put an end to the beast's killings, and also to take Marianne away. Upon his return, he finally sees the beast with his own eyes. It kills a man, but mysteriously refrains from attacking Marianne.
Fronsac, Mani, and the Marquis set out into the forest and set up an array of traps to capture the beast, but it proves to be too powerful and intelligent to be captured by any plan they make. After a violent encounter, Mani sets off alone, in pursuit, where he finds a catacomb used as the beast's holding pen, inhabited by the Brotherhood and a band of Gypsies working with them. These include Chastel, the beast's tender, and his daughter, whom Mani saved. Outnumbered and distracted by Chastel's daughter, Mani is shot in the back, overwhelmed and killed, but not before slaughtering a number of his attackers.
Fronsac is devastated when he discovers his best friend has been murdered. Performing an autopsy on Mani's body, he finds a silver bullet—Jean-François' signature choice of ammunition. In a fit of rage, a vengeful Fronsac goes to the catacombs, finding a pile of copies of L'Édifiante. He kills many of the Gypsies and discovers the beast's lair, before leaving so that he can burn Mani's body at dawn. After collecting Mani's ashes, he is overpowered by the local authorities and imprisoned. Sylvia visits him in jail and reveals to him that she is a spy for the Vatican. She explains that Henri Sardis, the local priest and leader of the Brotherhood, believes that he is restoring worship of God to France. Pope Clement XIII has decided that Sardis is insane, and sent her to eliminate him. She then poisons Fronsac, telling him he knows too much.
Henri Sardis decides to kill Marianne, and he persuades Jean-François to do so as a way to combat his incestuous lust for his sister. Jean-François comes to Marianne's room and reveals to her that he is the beast's master; it recognized his scent on her when it came near her, which is why it did not attack. He also reveals that his right arm is in fact intact, albeit badly scarred, and he has kept it hidden (his arm is seen stroking the beast earlier in the film). Jean-François then rapes and nearly kills Marianne.
Sylvia's agents exhume Fronsac, who had not been killed but merely put into a temporary coma, and he appears at one of the Brotherhood's secret sermons. In the resulting climactic battle, he kills several Gypsies and duels Jean-François to the death. The other members of the Brotherhood attempt to flee, but they are corralled and arrested by Captain Duhamel and his men. Sylvia, meanwhile, personally kills Chastel's daughter. Sardis escapes into the mountains, but is mauled to death by a pack of wolves (their leader being the same wolf that survived the previous slaughter, and was seen chasing the beast with its pack and seemingly bonded at a spiritual level with Mani).
Fronsac attempts to heal Marianne with a potion previously carried by Mani. He and the Marquis then go to the beast's lair, where Chastel is tending to it as it lies grievously wounded after the fight in the forest. It turns out the beast was an offspring of a "strange beast" that Jean-François brought back from Africa (which director Christophe Gans verifies is a lion). It was tortured into becoming vicious, trained to attack humans, and dressed in metal armor plating and spikes along with a large mask and metal implants in its jaw to make it more formidable and frightening. Fronsac takes pity on the dying creature and kills the beast in an act of mercy.
The film then returns to the opening time period of the French Revolution. The now-elderly Marquis d'Apcher finishes writing his account of the killings, just before he is led to his execution by a revolutionary mob. In the final scene, the Marquis has a flashback, in which he narrates that he does not know what happened to Fronsac and Marianne; but he hopes that somewhere, they are happy together. Fronsac is shown traveling to Senegal with Marianne to start a new life together, scattering Mani's ashes at sea. It is left unstated whether the two are alive and happy, or whether this is indeed the Marquis' dream.
gothic, murder, violence, atmospheric, flashback, good versus evil, action, tragedy