From the Bible code to the Voynich manuscript, from subtly altered hieroglyphs carved into ancient Egyptian monuments to clues hidden in Renaissance paintings, we are surrounded by mysterious codes bearing hidden messages from the past. What does it take to write a fail-safe code? What does it take to break one? Taking in the full history of code making, from the scribes of ancient Egypt to modern-day computer programmers, Codebreaker provides a fascinating insight into this most secret and mysterious of crafts. It shows just how Julius Caesar cunningly obscured the meaning of vital wartime messages and explains the way that Sir Francis Walsingham was able to use coded letter to foil plots against Elizabeth I. It gives an account of the ever-more complicated ciphers that were devised - and cracked - during the Cold War and investigates how codebreaking is being used today to fight crime and terrorism. And it shows you how to decipher codes from all periods of history, including many that are still employed today.