From the earliest days of mankind, people have sought to pass on secret messages via code so that only those who are supposed to understand the message can receive it. For almost as long, cryptographers have tried to break the codes. Most famous of all were those at Bletchley Park who managed to break the Nazis' 'unbreakable' Enigma code. Now, in this fascinating and intriguing book, Richard Belfield looks at some of the most difficult codes in history that have withstood years of investigation and shows the reader how they too can learn to solve or create almost any code. Sometimes, as with the notorious Zodiac Killer or the Voynich Manuscript, the codes remain unsolved, or as with Kryptos in the CIA's headquarters only 90 per cent has been decoded. Here, Belfield explains what the current theories are and provides avenues for further exploration. In the final element of the book, working with a team of top cryptographers from the Royal Holloway, the author sets his own code, based on the techniques that have been revealed throughout the book.Sure to intrigue all lovers of puzzles and codes, the winning person who deciphers the code will receive an original German World War Two Enigma machine, worth over 20,000.

Richard Belfield is an award-winning television producer and writer, making programmes investigating the death of Princess Diana and Yvonne Fletcher, among others. He is the author of Terminate With Extreme Prejudice, and two biographies of Rupert Murdoch.