In Europe, the Germans are still totally unaware that the allies have broken the complicated ENIGMA code, whilst in the Far East theatre, where the Japanese are using their own version of the ENIGMA code, an intercepted communication leads Brigadier Donald Reisman, head of British Intelligence in Calcutta, to the damning conclusion that the war's most closely guarded secret is no longer secure. Can he afford to test his theory when, to do so, he must...