By 1942, the once big star, Constance Bennett, was no longer a box office draw and was making less and less prestigious films following her glory days in the 1930s. Evidence of this is "Madame Spy", a cheap B-movie that was, frankly, beneath her talents.
When the story begins, a famous war correspondent, David Bannister (Don Porter), meets and marries Joan (Bennett). They seem very happy and she follows him about the globe covering the war. However, after a while, Joan behaves oddly and David begins to wonder if his wife might actually be an Axis spy!!
The story is illogical. I'd say more but it would betray the big plot twist...something that really didn't catch very many folks by surprise. It also is WAY over the top as a preachy propaganda movie (it probably made some HATE the war effort instead of getting behind it). However, I must also admit that the movie IS entertaining...if a bit silly.