Phil Vasco inherits a house in the mountains. After he and his young wife, Peggy, move into the house, they learn that the local people believe that a werewolf roams the valley during every full moon.
Soon after moving in, Phil is bitten by an animal during a hike in the woods and begins to act strangely. The locals warn her that he may have been bitten by the werewolf, which would cause him to also become a werewolf when the moon is full.
He acts more and more strangely as the date of the full moon approaches, and Peggy begins to panic.