Lee Publications YES & Know Mr. Mystery Secret Agent Spy Invisible Ink Game Book Be a super detective! Use your special pen to uncover the truth and solve the mysteries. Here are just some of the games you will find inside this book, decode the cryptograms, decipher Krazygrams, and nab the crook in jailbreak. Book Includes: special pen and 48 pages of fun Book Size: 6" x 11" Ages 8+