Valerie (Seyfried) is a beautiful young woman torn between two men. She is in love with a brooding outsider, Peter (Fernandez), but her parents have arranged for her to marry the wealthy Henry (Irons). Unwilling to lose each other, Valerie and Peter are planning to run away together when they learn that Valerie's older sister has been killed by the werewolf that prowls the dark forest surrounding their village. The people have maintained an uneasy truce with the beast for years, offering the creature a monthly animal sacrifice. But under a blood-red moon, the wolf has upped the stakes by taking a human life. Hungry for revenge, the people call on the famed werewolf hunter, Father Solomon (Oldman), to help them kill the wolf. But Solomon's arrival brings unintended consequences as he warns that the wolf, who takes human form by day, could be any one of them.