NATIONAL GEOGRAPHIC – Sunday 16 November, 10.30pm

From Julius Caesar’s simple but effective cipher, to the electro-mechanical codes of World War Two, explore how codes and ciphers work and chart their dramatic impact on world events. Secret information passes every second of every day across continents using codes known only to the sender and recipient. Every time you log your computer onto a favourite website, go shopping, use your phone and drive a car, you’re using secret codes. While quantum supercodes are set to be the way of the future, thousands of enthusiasts, professionals and geeks all over the world devote their lives to cracking some of the greatest – and strangest – unsolved mysteries concealed in codes, like the Zodiac killer’s predatory notes, the Papacy’s secret codemakers and the lost treasure of the Beale papers.