"The Final Problem" is a short story by Sir Arthur Conan Doyle featuring his detective character Sherlock Holmes. It was first published in Strand Magazine under the title "The Adventure of the Final Problem" in December 1893. It appears in book form as part of the collection The Memoirs of Sherlock Holmes. This story, set in 1891, introduced Holmes's archenemy, the criminal mastermind Professor James Moriarty. Conan Doyle later ranked "The Final Problem" fourth on his personal list of the twelve best Holmes stories.
Holmes arrives at Dr. John Watson's residence one evening in a somewhat agitated state and with grazed and bleeding knuckles. Much to Watson's surprise, he had apparently escaped three separate murder attempts that day after a visit from Professor Moriarty, who warned Holmes to withdraw from his pursuit of justice against him to avoid any regrettable outcome. First, just as he was turning a street corner, a cab suddenly rushed towards him and Holmes just managed to leap out of the way in time. Second, while Holmes was walking along the street, a brick fell from the roof of a house, just missing the detective. He then called the police to search the whole area but could not prove that it was anything other than an accident. Finally, on his way to Watson's house, he was attacked by a thug armed with a cosh. Holmes managed to overcome his assailant and handed him to the police but admitted that there was virtually no hope of proving that the man was in the employ of the criminal mastermind.