The Spy in Black is a 1939 British film, and the first collaboration between the British filmmakers Michael Powell and Emeric Pressburger. They were brought together by Alexander Korda to make the World War I spy thriller by Joseph Storer Clouston into a film. Powell and Pressburger went on to make over 20 more films together.
The Spy in Black, which was released in the US as U-Boat 29, stars Conrad Veidt, Valerie Hobson, Sebastian Shaw and features Marius Goring.
This film was named by the National Board of Review as one of the ten best films of 1939.
(Summary from Wikipedia)