Harry Lloyd, a former British officer turned diplomat and currently assigned to the British Embassy in Washington as military laison, is called upon to retrieve the best kept secret of the war; the Enigma ciphering machine. The Germans will soon occupy the British Isles and they must not discover the existence of the machine. Harry, at the request of Churchill and the American president, returns to England to recover the machine. Harry discovers that the new government, for fear he may try to rally the British people from exile, is detaining Churchill. Harry knows that the arrival of the Germans spells grave danger for Churchill and alters his plans to include the rescue of the former Prime Minister.
Harry allies with Anthony Eden, British Foreign minister and friend of Churchill, and William 'Wild Bill' Donovan, an American on an observation mission in England, to retrieve the Enigma and rescue Churchill. Time is short and together with George, a former bodyguard for Oswald Mosley, the leader of the British Fascist Union, they put Harry's plan into action. An attack on Harry and a close encounter with a German SS General are some of the obstacles overcome by the men in accomplishing Harry's mission.
