At Bletchley Park, Tom Jericho, a brilliant young codebreaker, is facing a double nightmare. The Germans have unaccountably changed their U-boat Enigma code, threatening a massive Allied defeat.

As suspicion grows that there may be a spy inside Bletchley, and Jericho is suspected, his girlfriend, the beautiful and mysterious Claire Romilly, suddenly disappears. With the help of Claire's best friend, Hester, Jericho sets out to find Claire, clear his name and unmask the spy. The answers will change his life forever.

Steeped in the atmosphere of wartime England, based around an actual event, Enigma is a thriller of genius: a compelling mystery of codes and codebreaking, love and betrayal set inside the birthplace of the secret state.