Mr. Verloc is part of a gang of foreign saboteurs operating out of London. He manages a small cinema with his wife and her teenage brother as a cover, but they know nothing of his secret. Scotland Yard assign an undercover detective to work at the shop next to the cinema in order to observe the gang.—Col Needham
A Scotland Yard undercover detective is on the trail of a saboteur who is part of a plot to set off a bomb in London. But when the detective's cover is blown, the plot begins to unravel.