The Spy in Black

Conrad Veidt - Captain Hardt
Sebastian Shaw - Lt. Ashington/Cdr. Davis Blacklock
Valerie Hobson - Frau Tiel/Jill Blacklock
Marius Goring - Lt. Schuster
June Duprez - Anne Burnett
Athole Stewart - Reverand Hector Matthews
Agnes Laughlin - Mrs.Matthews
Helen Haye - Mrs. Sedley

German submarine commander Captain Hardt lands at Malkirk, one of the Orkney Islands on the northern coast of Scotland, where his contact, the schoolmistress, tells him that he is to sink ten British ships in the local harbour with the help of a treacherous British seaman, Lieutenant Ashington. Unknown to Hardt, both Ashington and the girl are working for British intelligence, who have intercepted the real German spy and replaced her with a British agent.

Ashington arranges for the girl to leave on a ferry carrying prisoners-of-war, but Hardt escapes on the same vessel and leads a group of Germans to mutiny and take over the ship, only for it to be torpedoed by his own submarine. A British destroyer lifts the passengers off the stricken ferry, but Hardt refuses the offer of help. His submarine, meanwhile, has been sunk by the British fleet, its crew perishing in the same waters as their captain.