Mr. Creacher, a multi-tentacled substitute teacher, warns his prankish students not to misbehave, recounting rhyming cautionary tales of the weird, spooky, and unexpected.
The students in Mrs. Green's class are excited to hear they will be having a substitute teacher, but their plans for partying and having fun all day change when they see who the sub is and what he has planned for the day.
Little Bill, afraid to go to school because there is going to be a substitute teacher, is reassured by his mother who helps him remember that new things, while sometimes scary at first, usually turn out just fine.
Strange things start happening to Lizzie and her friends on Valentine's Day, and when their substitute teacher disappears, they all have to work together to try and find him.