Produced and directed by Roy William Neill, it stars Rathbone as Sherlock Holmes and Bruce as Dr. Watson, with Hillary Brooke as the woman of the title and Henry Daniell as Professor Moriarty.

Widower Sir George Fenwick, after a romantic night at the apartment of Lydia Marlowe, is hypnotized into believing that he is responsible for the crimes.

He leaves, and minutes later, Moriarty appears and explains that he faked the phone call so he could talk to Holmes.

Holmes explains what Moriarty did, notices that a window shade that was shut in the empty house across the street is now open, and tells Watson to investigate.

Inside the empty house Watson believes that he sees a sniper shoot Holmes in his apartment through the open window.

He then tells Holmes to write a suicide note (which he does), walk out of Lydia's apartment onto the ledge, and jump to his death.