Undercover is a 1943 British 'Ealing Studios' drama WWII film. It features John Clements, Tom Walls, Mary Morris, Rachel Thomas, Stephen Murray, Godfrey Tearle, Michael Wilding, Charles Victor, Niall MacGinnis, and Stanley Baker.
German occupied Yugoslavia. With organised resistance shattered by the Nazi onslaught it is only the activity of small guerrilla bands that bring fresh hope to the people. But quislings and infiltrators are everywhere, and trusting the wrong person could easily get you killed.