 When the Germans march into Prague, armour-plating inventor Dr Bomasch flees to England. His daughter Anna escapes from arrest to join him, but the Gestapo manage to kidnap them both back to Berlin. As war looms, British secret service agent Gus Bennet follows disguised as a senior German army officer. His ploy is the not unpleasant one of pretending to woo Anna to the German cause.