Starring Conrad Veidt and Valerie Hobson.
A Danish merchant ship gets forced by the British navy to dock at a British port for inspection. 2 passengers sneak off the ship and the Danish captain goes after them, to bring them back to the ship.
In my opinion, this film is right up there with the likes of Casablanca, with Humphrey Bogart!
https://www.youtube.com/watch?v=6hWV6cOHOyA
There are some very dark night scenes, so you will need a good monitor and graphics card, to eke out the details of the scenes.