Ralphie is convinced that Ms. Frizzle is a vampire when she shows up outfitted in a cape, speaking with a Transylvanian accent, and moving and talking like a vampire. The Friz is now taking all the kids's parents on a little field trip and Ralphie is convinced she is going to do something horrible to them. This episode teaches that the majority of bats are not vampires, and that they are fascinating creatures.