Set in the Victorian Age and regarded by many as the finest of the fourteen films in the Sherlock Holmes/Basil Rathbone series; `The Adventures of Sherlock Holmes' was originally released in 1939 by Twentieth Century-Fox.

Professor Moriarty (George Zucco) has at long last been brought to trial for murder; but the `Napoleon of Crime' is acquitted after the court finds a lack of sufficient evidence. Moriarty wastes no time in plotting his next crime; but in order to be successful he must divert the attention of the Great Detective.

Intimidating; anonymous letters sent to young socialite Ann Brandon (Ida Lupino) ; the murder of Miss Brandon's brother; and threats to the security of a priceless gem consume the attention of Sherlock Holmes (Basil Rathbone) and his companion Dr. Watson (Nigel Bruce).

Are these mysterious occurrences simply erroneous distractions? Are they clues to a case irrelevant to the exploits of the evil Professor Moriarty? Or; are these portents of disaster inexorably linked to the master criminal's plan to commit a crime that will shake the very foundation of the British Empire? It is for Holmes and Watson to sort out these mysteries and; hopefully; eliminate the menace of Professor Moriarty.