Alexander is used to finding monsters everywhere in Stermont, but now the school is being turned into an icebox by giant meat-eating vegetables--and his friend Rip has gone missing.

Alexander's class is going on a sleepover at the Stermont Museum, but something is stealing bright, shiny objects from all over town, including the museum's treasured Ruby Scorpion, and on the night of the visit the young monster hunters finally confront the town's newest monster--a warrior covered entirely by bubble-wrap.

It is the first day of the brand-new Stermont Elementary School, but everything electrical seems to be going haywire, and it looks like strange green lightning bugs are draining off the power--but when they see green lightning in a clear blue sky Alexander and his friends know there must be a monster involved.

When Alexander and his friends find a very large footprint and piles of candy everywhere, they realize the school is being threatened by a Pi�nata-saurus Rex, a sweet-tasting monster who likes to smash things--and they find that the solution may be as near as a broken ant farm.

The Notebook of Doom is missing and Alexander and his fellow-monster hunters, Rip and Nikki, are convinced that the boss-monster has it; but is that monster the mysterious Principal Vanderpants, who is certainly behaving oddly, or someone else--and they need to figure that out quickly because a mistake could have deadly consequences for Stermont Elementary.

In the year since Alexander and his father moved to Stermont, he and his friends in the Super Secret Monster Patrol of Stermont Elementary have defeated all kinds of monsters, but now they face their greatest challenge, the boss-monster who has kidnappedfellow monster fighter Ms. Vanderpants and stolen the Notebook of Doom--and they have to do it before Alexander turns eight and stops being able to see monsters.