A history of codes and code breakers from the former "Tomorrow's World" producer whose "Fermat's Last Theorem" went straight to the top of the UK non fiction bestseller charts and was translated into 22 languages. Subtitled "The Secret History of Codes and Code-Breaking", Singh unravels how codes and cyphers from Ancient Egypt all the way up to present day computer encryptions work, and also asks why we have such a yearning for secrecy. Popular science on a subject for which, as the success of recent "Enigma" and Bletchley Park titles shows, there is a proven appetite.