Seldom out of the news for long, code-breaking has had a bad time in the media so far, readers and viewers often finding it as perplexing as it is intriguing. As one of the greatest achievements of the century, code- breaking is a fascinating story, but all too often misunderstood and felt to be obscure. The author covers the story from the early code-breaking efforts through the rickety structure of the pre-war Government Code and Cypher School to Bletchley Park where a large powerful organisation arose, unscrambling thousands of secret enemy messages every day. Detailing how these amazing discoveries were actually used, taking us briefly into some of the battles of the Second World War, and in some detail the Battle of the Atlantic, when Britain was in danger of starving and where the war was nearly lost. For the first time, the code-breaking story with all its complexities is told in a straightforward and readable manner, whilst at the same time it will not fail to intrigue and astonish readers.