Activity books have never been so super secret! This fun, sturdy package comes with an invisible ink pen and includes invisible secrets throughout the book for you to reveal with the UV light in the pen's cap! Activities include: doodles, pranks, codes, jokes, dot-to-dots and more -- made all the more exciting with invisible ink. Plus, there are secret messages, a fingerprint-matching mystery to solve, and even a scavenger hunt scattered throughout the pages!