WWI thriller in which a German officer, nursed by a woman at the front who Is a Russian spy,marries her without knowing.Later after being separated he encounters her in Warsaw, where he's been sent to spy on behalf of the Germans.
Vintage magazines
Filmwelt 51, 20. Dezember 1931
Filmwelt 2, 10. Januar 1932
Books with substantial mentioning of Unter falscher Flagge