No one takes Spencer Zumbro seriously when he tries 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 friend, Daisy, Spencer has to find out what the janitors know. The children's search uncovers the existence of Toxites, small creatures that feed on the brain waves of students, and the evil organization known as the Bureau of Educational Maintenance (BEM).

Spencer and his friends are drawn into a battle between the secret society of janitors with wizard-like powers and the evil BEM. Along the way, they must perfect their Toxite-fighting skills, find the source of all magical Glop, and follow a trail of clues to the hiding place of the mysterious Aurans, who are guardians of a secret landfill. But time is short. With the fabled Manualis Custodem in hand, Spencer must also figure out how to summon the founding witches if they ever hope to mop up and save education.

This best-selling series is a gripping ride through conflicted loyalties and daring escapes, unexpected alliances and betrayals, and an ending you'll never forget