Cyd turns into a menacing werewolf when she accidentally gets some of Barry's wolf serum on herself. Shelby then tries to figure out how to counteract the serum before the she-wolf destroys the school's Halloween carnival.

The time-traveling besties' friendship is in trouble when Shelby learns Cyd went to a concert without her and lied about it. Meanwhile, Bret and Chet try to earn their camping badges from the safety of their backyard.