Sam, Lucy, and Antonio have a new substitute teacher, who happens to be the great-great-grandson of Orson Eerie, the evil scientist whose spirit possesses and infects their elementary school--and the friends are afraid he may be trying to bring Orson back to life.

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.

A heavy snowstorm traps the students inside Eerie Elementary, a living, breathing monster brought to life by mad scientist, Orson Eerie--soon the school begins to freeze from the inside out, and Sam, Lucy and Antonio must find a way to get the heat back on before all the students freeze to death, while facing the truth that Orson Eerie is even more powerful and dangerous than they realized.

Eerie Elementary is planning a big Halloween-type celebration for Eerie Day, including hosting a "haunted house" at the school itself; but the spirit of the evil scientist Orson Eerie sees this as the chance to finally triumph over the intrepid hall moniters, Sam, Lucy, and Antonio--and it is up to them to prevent a catastrophe and perhaps even defeat Orson and banish him from the school forever.

Sam Graves discovers that his elementary school is alive and plotting against the students, and, as hall monitor, it is his job to protect them--but he will need some help from his friends.