Someone has stolen X Middle School's beloved mascot, Lobstee the Lobster. Time is running out for both Lobstee and the Bocce Team, and the key to finding him before time runs out might be X's resident psychic, Alistair Greystone.

After accidentally destroying Folsom's birthday party, Fillmore and Ingrid are asked to do convention duty. However, the train convention experiences sabotage, leaving the entire convention ruined. Fillmore and Ingrid first suspect the RC Car Club to be behind it, but the evidence points in the other direction.

Fillmore's partner moves away to Tennessee, and he is partnered up with Brad Parnassus, the smartest kid at X Middle School. Rebellious and super-smart new student Ingrid Third doesn't take her introduction to X student body well at all, and a giant stink bomb soon explodes in the hallways.

Mrs. Lawson's field trip to the Modern Contemporary Natural History, Art, Science and Miniature Museum takes a horrifying turn as someone draws a mustache on the priceless painting "The Lobster Man at Port". Fillmore, Ingrid, and O'Farrell work to find the culprit and save the painting, but the clock is ticking and everyone's a suspect.

Scooter thefts are up, and the Safety Patrol faces a challenge from student activist Derek Minna, who establishes B.A.G.A.S.T. (Boys And Girls Against Scooter Theft), a scooter and rollerblade equipped task force that he intends to ultimately replace the safety patrol. Fillmore and Ingrid trace the thefts to the Metal Shop and infiltrate the gang in an attempt to take down the culprits.

Tina and Toby are the stars of the school at both dancing and smoit-collecting. Smoits are tokens found on dairy bars and packets of chips used to buy basically anything a kid could want once enough of them are saved up. The smoit stash goes missing, and Fillmore and Ingrid go undercover in X's steamy underground casino scene. They discover Toby's gambling debts, and he becomes the prime suspect, which destroys his dance partnership with Tina.

Fillmore and Ingrid investigate the mysterious vanishing of a student named Alexis, only to find that all reports of her have vanished from the school, and she's even been taken out of pictures. Meanwhile, someone is working on a computer virus called Electric Haircut, which must be stopped before it causes any irreparable damage.

The Ultrabox, the hottest new game system on the market, makes its debut at X, and everyone wants one—including "The Maestro," a gaming mastermind who will stop at nothing to get it. Fillmore and Ingrid track him down, but the Ultrabox is stolen while he's in custody. It looks like a copycat is on the loose.

Facing expulsion under Principal Folsom's new "Three Strikes, You're Out" rule, Fillmore must protect the only person capable of clearing his name to a crime he has been framed for—the destruction of a giant Folsom statue made out of 12,000 pieces of macaroni.