No one takes Spencer Zumbro seriously when he tried to warn his classmates about the mysterious things prowling the halls and classrooms of Welcher Elementary School. But when he sees Marv, the janitor, going after one of the creatures with a vacuum, he knows he's not the only one who can see them.

With the help of his new friends, Daisy, Spencer has to find out what the janitors know. The children's search uncovers the magic taking place behind the scenes of their seemingly ordinary school, where a battle is being waged for the minds of the students. Who can be trusted—and can Spencer and Daisy protect their school and possibly the world?