This
Casablanca
-esque spy thriller set during WWII centers on the exploits of the notorious "Flying Dutchman," a fugitive resistance leader from Holland who heads for Lisbon where he hooks up with other members of the underground. One of them is a beautiful young woman, and none of the others trust her because she is married to an important German official. For the resistance leader, real trouble comes when he is framed for the murder of a fellow agent. Still he escapes from prison and hides out with his other colleague while he works to prove that he is innocent and carry out a major secret mission for the resistance.