Don't let your secrets fall into enemy hands! With this handbook, you'll learn everything you need to know in order to create and break over 50 different codes and ciphers, using mobile phones, crossword puzzles, lemon juice and other ingenious methods. Children will have lots of fun sending secret messages to their friends and trying to decipher their responses. Short and entertaining activities for each code enable the young super-spy to master the rules of the code before trying it out for real.