During the heart of World War II, in March of 1943, cryptoanalysts at Britain's code-breaking center have discovered to their horror that Nazi U-boats have changed their Enigma Code. Authorities enlist the help of a brilliant young man named Tom Jericho to help them break the code again. The possibility of a spy within the British code-breakers' ranks looms and Tom's love, Claire, has disappeared. To solve the mysteries, Tom recruits Claire's best friend, Hester Wallace. In investigating...