The student body is in an uproar when the controversial S.A.T.T.Y. 9 tests are stolen by an assailant dressed as X's beloved mascot, Lobstee the Lobster. Fillmore and Ingrid are under pressure—they have only 48 hours to find the tests or Principal Folsom will have the entire school take the tests again.

The library's books have disappeared, and Tony Clementina, X Middle School's local heavy, is all too eager to take credit for it. Meanwhile, an empty can of Carbee Cola leads Ingrid back to the biggest custard spill in X Middle School history, an incident that disturbingly points to Fillmore.

Duappy, a virtual pet kept alive the longest, has been stolen, and it is up to Fillmore and Ingrid to find X's pride and joy before a reporter comes to X to do a story on Duappy and before Duappy dies.

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.

Vallejo's nearing his second term test for Junior Commissioner, and in the meantime, a crime crops up involving "The Shredder", an anonymous criminal who shreds people's pet projects. Unfortunately, not a single one of the victims saw the Shredder's face. This seems like a job for Vallejo's old profiler partner, Frank Bishop, who was driven from the Safety Patrol in disgrace. He is tasked to deduce a pattern to the Shredder's crimes and discover who is next on the list.

Reformed thug Linus Santiago wows the crowd at the X Middle School Talent Show with his magic act. Unfortunately, his disappearing trick with Dewey Hubble's robotic dog Barcode goes horribly wrong and it won't reappear. Santiago refuses to tell the Safety Patrol how he did the trick due to the Magician's Code, but by doing so, he makes himself the prime suspect. Dewey is anxious to get his robotic dog back as it's a stepping stone to getting a real dog. However, when Barcode's collar is found in the lake, all hope could be lost—for both Dewey and Santiago.

Something's down at the X Middle School Open—professional golfers are failing at games, and foul play is suspected. Normally, Fillmore would be all-up for an undercover job like this, but something in his past is making him hesitate.