Secret War in Portugal [1939-1945]
For SOE [British Special Operation Executive] 24 Land was the code name for Portugal

The Conspirators

Vincent Van Der Lyn, a Dutch freedom fighter in WWII, is forced to neutral Lisbon to escape the Nazis. There he meets a small band of underground conspirators. The group's leader, Ricardo Quintanilla, knows that one of their number is spying for the Nazis, and needs Van Der Lyn to help identify the traitor. Directed by Jean Negulesco, Starring Hedy Lamar, Pau Henreid, Peter Lorre and Sidney Greenstret. Written by Ken Yousten [see here about him and here about the movie].