Once Upon a Honeymoon - Leo McCarey

At the start of WWII, Katie O'Hara, an American burlesque girl intent on social climbing, marries Austrian Baron Von Luber. Pat O'Toole, an American radio reporter, sees this as a chance to investigate Von Luber, who is suspected of having Nazi ties. As country after country falls to the Nazis, O'Tool follows O'Hara across Europe. At first he is after a story, but he gradually falls in love with her. When she learns that her husband is indeed a Nazi, O'Hara fakes her death and runs off with O'Toole. In Paris, she is recruited to spy for the allies; he uses a radio broadcast to make Von Luber and the Nazis look like fools.