Nazi spies, including William Easter (Henry Daniell), have followed Sir Henry Marchmont (Gilbert Emery) to America only to realize that he is a decoy for John Grayson (Gerald Hamer), senior clerk for solicitors Farlow Nash and Farlow (and also an agent for the British Secret Service). Grayson is carrying a secret document, which was given to him as two legal-sized pages, from London to New York by air and from New York to D.C. by train. In the train’s club car Grayson recognizes that he has been twigged and bumps into Senator Babcock (Thurston Hall) on purpose in order to have someone close to him. They order drinks at the bar and take a table, and as the spies move in, Grayson speaks to three other passengers. One of them, Miss Nancy Partridge (Marjorie Lord) is about to smoke a cigarette, so Grayson gets a match book out of his pocket and lights it for her, dropping the matchbook into her open purse. When Grayson tries to leave the car he is kidnapped, but has nothing on him.
Back in London, the government seeks out Holmes and asks him to go to Washington to find Grayson and the document. When he and Watson check into their hotel room, a trunk is delivered containing Grayson’s body.
Sherlock’s hunt for the spies, the document, and Nancy (who has been kidnapped) makes for a suspenseful and satisfying film. George Zucco plays Mr. Stanley, the head of the spy ring, and John Archer plays Lt. Pete Merriam, Nancy’s fiance, with Don Terry as Howe, Stanley’s most prominent henchman.
After retrieving the document, saving Nancy, and capturing the spies, Holmes and Watson are leaving D.C. and this exchange occurs in a cab headed for the airport and driving directly toward the Capitol.
SH: This is a great country, Watson.
DW: It certainly is, my dear fellow.
SH: Look up there ahead – the Capitol, the very heart of this democracy.
DW: Democracy. The only hope for the future, eh Holmes?
SH: It’s not given to us to peer into the mysteries of the future, but in the days to come the British and American people will, for their own safety and for the good of all, walk together in majesty, in justice, and in peace.
DW: That’s magnificent. I quite agree with you.
SH: Not with me, but Mr. Winston Churchill. I was quoting from the speech he made not so long ago in that very building.
Screenplay by Bertram Millhauser and Lynn Riggs, Original Story by Bertram Millhauser, Directed by Roy William Neill.