Alexander has just moved into Stermont, but the elementary school is being torn down, his new classroom is located in the hospital morgue, a notebook he finds is full of information about monsters--and everywhere he turns there are spooky balloon men determined to attack him.

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.

Alexander's class is going on a field trip to an amusement park called Safety Land with really slow, boring rides--but this is Stermont, and when a weird magician tells Alexander and his friends that the roller coaster is haunted things start to get a lot more interesting.

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 kidnapped fellow 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.