An excellent little wartime spy drama. Andersen (Conrad Veidt) is the captain of a neutral Danish freighter which is impounded by the Royal Navy to check it's cargo. Two of his passengers, Mrs Sorensen (Valerie Hobson) and Mr Pidgeon (Esmond Knight), jump ship and head for London. Andersen goes in pursuit, he catches up with Sorensen and soon finds he is involved in a cat and mouse fight between British and German agents.
Andersen and Sorensen end up the prisoners of the Germans in a basement lair. Andersen manages to escape and enlists the help of some of his countrymen to save the day and more importantly Mrs Sorensen...
An exciting film full of derring-do that makes the most of a modest budget. Filmed when it was, just as the war was starting, the propaganda is dialled back and the Germans are mostly portrayed as doing their duty as opposed to just being evil. The growing relationship between Andersen and Sorensen is well portrayed and very believable.