The Cryptid Club has found its next case! When they discover strange writing on the bathroom stalls and that something is stealing paper and pens, they know it's going to take some super sleuthing to crack this caper. But when a monster starts popping upin every toilet around the school, the principal orders all the bathrooms immediately closed. Now Lily, Henry, Oliver, and their superhero-wannabe friend, Ernie, must solve the mystery before the whole school can't hold it in any longer!