It has been several months since monsters last plagued the town of Stermont, and frankly Alexander Bopp (leader of the Super Secret Monster Patrol) is bored, and misses his friends Rip (immersed in video games) and Nikki (soccer camp), so when his father signs him up for a summer maker program at the library he is happy to go--but soon he starts finding weird old-timey objects, and monster trading cards, and it starts to look like maybe monsters are...

Alexander and his new friend, Rip, are worried that the worms the rain has brought out are really the megaworms that Notebook of Doom describes but they soon discover that the night crawlers are trying to warn them about the monster tunnel fish that are threatening Stermont Elementary.

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.

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.

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.

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.

It has been a busy summer of makerspace projects at the library and monster hunting for the three members of the Super Secret Monster Patrol, and the puddles that are appearing all over town are a clue to the identity of another monster--an angry hydra water monster who is obsessed with cleaning up (literally) the town of Stermont, even if it means drowning all the messy children who live there.