Since the Notebook of Doom was stolen Alexander and the other monster hunters of Stermont Elementary have been operating without its assistance and now they are confronted by a large and stinky monster with eight powerful noses that can deliver a slimy sneeze with the power of a cannon--and somehow they must figure out its weakness.

It is a very hot summer in Stermont, and Alexander and his friends are at Camp Gloamy in the mountains, but even here there are monsters--specifically zombie snowmen called snombies who want to freeze the young monster-hunters.

When Alexander and his friends find a very large footprint and piles of candy everywhere, they realize the school is being threatened by a Piñata-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 latest monsters threatening Stermont Elementary are shadowy shapeshifters that attach themselves to people, eat their shadows, and block out all light--but before he can think of a way to deal with them, Alexander has to deal with a startling revelation from his friend Nikki.