When Billy Dilley's science fair project the Cheeserator gets struck by lightning and goes haywire, Billy and his lab partners Zeke and Marsha find themselves stuck in a strange underground land called Subterranea-Tania.
Billy, Zeke and Marsha must find their way back to the Cheeserator using their "Survival Skills".
Zeke, the "King of Calzones", must defend his title when a rival chef enters the picture.
Billy invents a grafting machine and starts adding different creature parts to his body.
When Marsha learns she has missed her date with her summer camp crush Greg Hastings, Billy and Zeke attempt to cheer her up by fixing her up with a subterranean replacement.
Zeke feels intimidated by a primitive tribe called the Troggies, who can do everything better than he does.
Marsha starts a newsletter about Subterranea-Tania and Billy is desperate to know what she's written about him.
Billy strikes up a friendship with the sludge-obsessed Count Wretcher, who offers to help fix the Cheeserator for his own nefarious plans.