Dr. Watson assists in the investigation of the murder of Ronald Frances Adair and is shocked by the unexpected return of the presumed dead Sherlock Holmes. Together they nab the last remaining henchman of Sherlock's archenemy Moriarty.
Holmes is contacted by the King of Bohemia. The monarch wants Holmes to search for a photo in Irene Adler's possession which she can use to blackmail him. Despite Holmes' best efforts, Irene Adler is always one step ahead of him.
Adelaide Savage requests Holmes and Watson investigate her husband Victor. Victor Savage is addicted to opium and influenced by his wicked cousin Culverton Smith, who is intent on taking over the Savage family fortune.
Holmes and Watson investigate an odd vacancy Mr. Wilson applied for and lost two months later. Holmes finds that this was just to get Mr. Wilson out of the way in preparation for a bank robbery.
Sherlock Holmes is assigned to search for a top secret document, without arousing suspicion from the public. After days of investigating, Holmes finds the thief was blackmailed into taking it.