Pitting Sherlock Holmes (Basil Rathbone) against a wily female adversary named Mrs. Hilda Courtney (Patricia Morison) sets the great detective on a musical mystery. The case is called “Dressed to Kill.” When a friend of Dr. Watson (Nigel Bruce) is murdered, Holmes deduces that the music box he had just purchased may be a motive. With more logical insights, Holmes determines an intricate plot that could undermine the British economy with counterfeit money. He traces the problem to Mrs. Courtney who is collecting the music boxes, each containing part of an intricate plan for printing plates. Holmes believes he has met a match equal to his greatest case with Irene Adler, and Watson also draws parallel to the other crimes they have solved together as Holmes sees what Watson observes once again.