The Woman Alone (1936)

Alfred Hitchcock, Sylvia Sidney, Oskar Homolka, Charles Hawtrey

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