The kids' history teacher eats a worm in detention, giving him the powers of an ancient warrior. He then hypnotizes Sue and Sid, leaving only Tobey to find the anecdote before an army of mind-controlled kids complete the Great Wall of Chinatown.
An orange gas permeates the town and causes the residents to have hallucinations based on their greatest fears. Nana and the kids go to confront Kong Li about it, but they get exposed to the gas in the process.
After a boy doesn't take proper care of his mysterious new pet Bok Choy, a mob of evil Bok Choys plagues Chinatown. Nana cooks up an antidote, for which the kids prepare the monsters by soothing them with Mr. Wu's karaoke machine.
A kid named Jason prepares a recipe that disrupts the balance that exists between Chinatown and the underworld. Soon, boar soldiers arrive in town looking to kidnap Jason, whom they want to be their new leader in the underworld.
Mr. Von Yang concocts a recipe to bring his brother back from the dead, but he accidentally brings back the Jiangshi zombies instead. Tobey and Sue need to reverse the recipe by midnight, or the Jiangshi will remain on Earth forever.