This is a book by Fatherland author Robert Harris. It is a fictional account of espionage and deception happening in Bletchley Park, England during WW2. The protagonist Thomas Jericho is an ace mathematician and cryptographer who has suffered a nervous breakdown immediately after helping break the notorious Shark cipher used by German u-boats. And he has to go back and break it again because the Germans have shut off Bletchley’s only way into the cipher.
What is unique about this book is the fact that the author has used actual message intercepts and woven them neatly into the storyline. The book has been made into a movie of the same name (Enigma (2001) – starring Dougray Scott and Kate Winslet).
Want to know more about Enigma – the cipher machine? Visit Enigma.