An American Werewolf In Canada - Monica Muniz - Bog

Teenage boy Karl is missing and everyone thinks that the troubled youth is dead...except Frank. Frank knows that his best friend is out there and that Karl will come back. Six months later, Karl does return with no idea of what happened to him. He gets reacquainted with their high school clique but everyone senses that something about Karl is different. After a weekend retreat, they realize that Karl is more than just different...he's a werewolf and when the full moon arises they find themselves fighting for their lives.