The ultimate super secret with notebook! The Ultimate Invisible Ink is full of hidden messages, secret codes, games, jokes, and more activities to help bust even the most unbeatable boredom. You'll see both visible (and invisible) activities, fun facts, and mysterious messages throughout the 64 full-color pages and uncover invisible ink printed notes and images on every page. Included is one UV pen to write and reveal hidden messages in the book or on your own!