"Want to learn how to make and break top secret messages like a real spy? IF so, this is the book for you! Inside are more than 80 pages of tips, tricks, and practice exercises for writing and deciphering cryptic communications. You'll learn how to make your own invisible ink, hide your messages, create unbreakable ciphers, and craft your own decoder gadgets. You can use this manual to learn how to exchange top secret notes with friends"--Page [4] of cover.