Violet Smith, a young music teacher, contacts Holmes when she is followed by a mysterious cyclist; Holmes connects this with her employer's marriage proposal.
A solicitor who was asked by a man he had never met to draw up a will leaving the man's fortune to himself consults Holmes after he's been accused of murdering the man.
After foiling Moriarty's plan to steal the Mona Lisa, Holmes survives several attempts on his life from Moriarty's agents; the two face each other for the last time at the Reichenbach Falls. (Last appearance of David Burke as Dr. Watson)
Holmes returns to England, to Watson's shocked surprise, and must stop a member of Moriarty's gang who is trying to assassinate him. (First appearance of Edward Hardwicke as Dr. Watson)
A rich duke reluctantly allows Holmes to search for his ten-year-old son who is missing from his boarding school along with the German tutor. (This is actually the sixth episode of the series and Abbey Grange is the second.)
While vacationing at the estate of his old university classmate Sir Reginald Musgrave, Holmes is called in when the scholarly butler disappears after being discovered reading an old document about a mysterious family ritual.
Holmes is contacted by Inspector Lestrade after the police are baffled by a series of burglaries serving only to steal and smash identical busts of Napoleon.
Mary Morstan has received a pearl in the post every year since her father's disappearance; this leads Holmes and Watson to the truth about a secret pact between four convicts during the Indian Mutiny of 1857.[1][2]
Holmes helps Mycroft when stolen top secret blueprints for a submarine are found on the body of a civil servant found dead on the tracks of the Underground.
Sir Charles Baskerville was found dead with a horrible expression on his face after seeing a mysterious demonic spirit of a gigantic hound that has haunted his family. Dr Mortimer visits Sherlock Holmes to save Sir Henry the heir of the Baskerville estate and to solve the mystery of the demonic curse before it's too late.
Holmes must help James McCarthy when his father is killed after an argument (the subject of which he will not reveal) and young McCarthy is accused of the crime.
Holmes and Watson attempt to thwart the schemes of the infamous blackmailer Charles Augustus Milverton from blackmailing Lady Eva Blackwell. But things do not seem as easy as they do and Holmes must sacrifice his morality and his honourable career to stop Milverton from wrecking her marriage.
Sherlock Holmes is called upon to investigate a series of deaths which seem to be related to John Stockton, who is descended from a family rumoured to have been vampires.
When Victor Savage begins using opium and behaving strangely, his wife consults Holmes. Victor dies, and Holmes suspects his cousin, knowledgeable in rare diseases.
Mycroft investigates when the Mazarin Stone is stolen from a museum, and Watson deals with the promise of a large inheritance if a third person with the surname of Garrideb can be found.