Bill Roberts is an American radio commentator station in Berlin in the months before Pearl Harbor. Having witnessed Nazi brutalities first hand, Roberts hopes to alert his listeners of impending dangers, and does so by sending out coded messages during his broadcasts. The Gestapo begins to suspect something and assigns glamorous secret agent Karen Hauen to spy on Roberts. When she discovers that her own father is supplying Roberts with vital secrets, she turns her back on the Nazis and joins our hero in his efforts.