A British spy infiltrates a group of foreign saboteurs operating in London, posing as a shopkeeper next to a cinema run by a seemingly ordinary family, unaware of the husband's true identity and activities.
A cunning Scotland Yard detective goes undercover to track down a ruthless saboteur threatening to devastate London with a bomb, only to have their identity exposed and the entire plan begin to fall apart.
A British spy infiltrates a group of foreign saboteurs operating in London, posing as a shopkeeper next to a cinema run by a seemingly ordinary family, unaware of the husband's true identity and activities.