While reading a werewolf Goosebumps book late at night under the full moon, Sam starts to feel strange and turns into one himself.

Late at night and under a red moon, Sam Talbot starts to feel funny. He drops his Goosebumps book about a werewolf and turns into one himself. Although he starts out like a normal teenager, he becomes a danger, with razor-sharp claws and fangs and a hangry attitude.