History's amazing secrets and codes—and how to crack them yourself.This fascinating look at history's most mysterious messages is packed with puzzles to decode and ciphers that kids can use themselves. Here are the encrypted notes of Spartan warriors, the brilliant code-crackers of Elizabeth I, secret messages of the American Revolution, spy books of the Civil War, the famous Enigma Machine, and the Navajo code talkers. As computers change the way we communicate, codes today are more intriguing than ever.From invisible ink to the CIA, this exciting trip through history is a hands-on, interactive experience— so get cracking!