Things are getting too hot in New York City for "Joker" Finnegan and his gang, so they decide to move their activities to London. There, Inspector Gray of Scotland Yard is keeping a polite eye on them as "Joker" is planning a big robbery of a large department store, known as the House of a Thousand Windows. "Joker" forces an American actor named Reilly to impersonate Mr. Sherwood, the store owner, as Reilly and Mr. Sherwood are identical in appearance. Ronald Martin, store employee and nephew of Sherwood , is fooled also, but he is much distracted by the romance he is having with another store employee, Joan.