A practical joker is on the prowl in the old Raven Hill Library. Liz, Sunny, Tom, Nick and Elmo think the tricks are funny, but Richelle doesn't agree. She thinks the library is a creepy place and the secret joker is making it worse.
Richelle is proved right when the jokes in the library turn nasty, and then become downright dangerous. Everyone agrees that the trickster has to be unmasked, before something terrible happens. And soon, whether she likes it or not, Richelle is plunged into a mystery that's no laughing matter.
