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.

For the first time in years Eerie Elementary is planning a science fair, which may not be a good idea in a school which is alive and out to get the students--but when Sam and his friends find a book of experiments that contains all of Orson Eerie's notes, it may turn out to be the key they need to finally understand the mad scientist.

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.

"Eerie Elementary is hosting a "haunted house" for the town's Eerie Day celebration! Sam, Antonio, and Lucy are excited about the holiday... But mad scientist Orson Eerie has his own plans. Pumpkins attack and Sam gets trapped on a haunted hayride! Can Sam and his friends find a way to save everyone? This will be their biggest battle yet!"--Page [4] of cover.

Something is stealing machine parts from all over Stermont, including a wrecking ball from a local construction site, and Alexander and his fellow monster hunters, Rip, and Nikki, fear that it is building a Stermont-smashing machine--so the friends must use the resources of the summer maker program at the library to stop this monster, and perhaps even solve the mystery of who is leaving monster trading cards where the Super Secret Monster Patrol can...