Lupin (Robert Lamoureux) is a jewel robber in pre-World War 1 Germany. Moving in the highest social circles, Lamoreaux has as much fondness for the ladies as he does for his ill-gotten gains. One of his conquests is played by Liselotte Pulver, who as Lilo Pulver costarred with James Cagney and Horst Buchholz in Billy Wilder's One Two Three (she's the girl in the polka-dot dress). Lupin proves to be a patriot when he robs the coffers of France's enemy-to-be Kaiser Wilhelm.
Source : allmovie.com