British Intelligence (1939)

"Although the home of cabinet minister Arthur Bennett is a hotbed of spies, moles, and double agents, no one knows the true identity of notorious German spymaster Strendler."

During WWI pretty German master spy Helene von Lorbeer is sent undercover to London to live with the family of a high-placed British official where she is to rendezvous with the butler Valdar, also a spy, and help him transmit secret war plans back to Germany.