Something strange is happening at Franklin Elementary...Max knew something was off the moment the new substitute showed up. Mr. Dross doesn't blink. He never uses the whiteboard. And he has very strong opinions about handwriting.But when homework starts disappearing-and so do the kids who turned it in-Max and his best friend Zoey uncover a secret too weird to be believed: their teacher might not be from Earth... and he's got a taste for loose-leaf.Now it's up to two fifth graders, a suspiciously fast former friend, and one very loud hamster to stop a quiet invasion-before school becomes permanently out.