Crowley bosses Dean and Sam and sends them to Buffalo, New York, to capture an Alpha werewolf that is killing people. Crowley would return Sam's soul if they succeed and bring the Alpha to him. Soon they discover that the killer is actually a skinwalker posing as the family dog Lucky that loves his owners Mandy and her son. He kills those that threaten the family to protect them. Dean and Sam catch Lucky and they discover that there are thirty skinwalkers living as family dogs and ready to transform their families into an army of skinwalkers. Now Dean and Sam want to destroy the pack and the Alpha.