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.

Verloc trabaja como gerente en un cine de Londres. Pero bajo esta idendidad se esconde el jefe de un grupo de agitadores extrangeros que se dedican al terrorismo