Plot
During the Second World War, a captured German spy (Marius Goring) is executed at the Tower of London, without revealing the whereabouts of Professor Hansen, a refugee Swedish scientist in Britain. He is believed to be unwittingly passing information on the atomic bomb to Germany through the neutral Irish Free State. British intelligence attempts to locate him and break this link.[4]
Two intelligence officers, Captain Grant and Captain Wilson, travel incognito on the overnight ferry to Dublin. They observe the German contact, Keitel, and their suspicion falls on lawyer Paul Faber. Grant manages to get a clerical job in Faber's London office, using a false identity. He allows himself to be exposed as an ex-army officer who's gone AWOL, and allows himself to be blackmailed by Faber into doing a number of illegal jobs. These include a marriage of convenience to Marion, a young Austrian girl who is desperate to acquire British nationality; also the theft of some radioactive items from a docks warehouse.
Eventually, the trail leads Grant, Hunter and the police to the fictional village of Hunstable in Devon, and from there to a cliff-edge mansion where Hansen is being hidden. A showdown in a sea cave under the mansion leaves the police triumphant.
Grant is directed to a room where his wife, Marion, is held. She expects a spy is entering and breaks a vase on his head. The film end with her kneeling next to him saying "Oh David".
Production
Filming took place in July 1945.[5] It was shot at the Welwyn Studios in Hertfordshire with sets designed by the art director Charles Gilbert.
