"The Adventure of the Final Problem" is the last of the short stories of Sherlock Holmes from the The Memoirs of Sherlock Holmes written by Sir Arthur Conan Doyle. It was first published in The Strand Magazine in December 1893. Conan Doyle later ranked "The Final Problem" fourth on his personal list of the twelve best Holmes stories. When Conan Doyle wrote it, he originally intended it to be the last Sherlock Holmes story, as he himself wished to move on to other literary pursuits.
One evening, Holmes visits Dr Watson looking thinner and paler than usual and with the knuckles of one hand burst and bleeding. Holmes asks Watson if he has ever heard of Professor Moriarty and Watson replies that he has not. Holmes explains that Professor Moriarty is the central organizational force of a large portion of criminal activity in the city of London. Holmes also describes Moriarty as his intellectual equal and the Napoleon of Crime.
Holmes has managed to weave a net around Moriarty and all the principal members of his gang. In a few days time everything will be concluded and the gang arrested but a premature move might ruin the plans.
Moriarty is fully aware of the planned move against him and has already confronted Holmes and warned him to back off or be crushed. After this interview, in which Holmes would not back down, three separate incidents occurred which nearly robbed Holmes of his life.
Watson agrees to accompany Holmes onto the continent for the few remaining days before the arrests are concluded. Holmes provides detailed instructions for Watson's journey to the station the next day and then leaves by climbing over the back garden wall.
In the morning Watson gets to the station without any trouble but Holmes is not in the carriage he had mentioned the previous night. An elderly Italian priest gets into the carriage despite Watson’s protestations but just as the train is preparing to leave, Watson hears Holmes' voice. The old man of religion is merely a disguise and Holmes had arrived safely at the station after all.
As the train pulls away, Holmes points out Moriarty rushing onto the platform. In order to throw Moriarty off their trail, Holmes and Watson get out at Canterbury but allow their luggage to progress on its journey and provide Moriarty with something to follow.
Holmes tries to persuade Watson to return to England for his own safety; since Moriarty is now ruined he will devote himself entirely to vengeance against the man who brought destruction upon him. But the faithful Watson refuses to leave his friend's side and the two of them continue to travel, next going to Switzerland.
Whilst staying in Meiringen Holmes and Watson plan to continue to Rosenlaui with a small detour to see the Reichenbach Falls. The falls are an awe-inspiring natural spectacle. A small path affords a view of them and also of a steep drop down into the rock bestrewn river below.
As they leave the falls a Swiss boy runs up to Watson and gives him a note. The note appears to be from their hotel proprietor who asks that Watson returns immediately to assist a dying woman.
Watson sets out for the hotel after arranging to meet Holmes that evening at Rosenlaui. On his way Watson notices a black clad figure (Moriarty) heading up the hill behind him. Upon reaching the hotel Watson is told that the letter is a hoax and that there is no sick woman at the hotel. Watson realises that the figure he saw was that of Moriarty and that the Swiss boy was probably acting for him.
Watson races back to the falls and is sickened to see Holmes' alpenstock leaning against the rock were he had left Holmes, but no sign of him. Watson finds two sets of footprints going out onto the muddy dead end path with none returning then discovers a letter folded up and left on a boulder underneath Holmes' cigarette case. The letter is from Sherlock Holmes to Watson. He writes that he is about to have a final confrontation with Moriarty. Holmes had known that the message from Meiringen was a hoax and decided to face his nemesis.
It is all too clear that during the fight that took place between Holmes and Moriarty, both fell to their deaths down the waterfall. The Moriarty gang are all convicted on the strength of evidence secured by Holmes. Watson ends his narrative by saying that Sherlock Holmes was the best and the wisest man he had ever known.
- Sir Arthur Conan Doyle had intended this to be the last Sherlock Holmes case, and thus he killed him off in what he perceived as a final act of glory. He felt the Sherlock Holmes stories were distracting him from more serious efforts, notably his historical non-fiction and spiritualism. After becoming financially desperate and viewing the overwhelming success of The Hound of the Baskervilles, he revived Sherlock Holmes in The Return of Sherlock Holmes.
- This is the only time Sherlock Holmes decided to flee from an adversary rather than face him directly.
- The Granada Television series' episode "The Final Problem", first aired in 1985. It was the last episode of The Adventures of Sherlock Holmes (i.e. the first two series of the ITV/Granada adaptations). Professor Moriarty was played by Eric Porter and was introduced in the previous episode.
- The 2011 film Sherlock Holmes: A Game of Shadows used "The Final Problem" as inspiration, though the film tells an entirely independent story. Like "The Final Problem", the film ends with Holmes financially crippling Moriarty and the two of them falling over the side of Reichenbach Falls.
- The first episode of the animated TV show Sherlock Holmes in the 22nd Century, "The Fall and Rise of Sherlock Holmes", was a continuation of this story.
- The BBC's Sherlock episode "The Reichenbach Fall" was based on this story. The special "The Abominable Bride" took elements from the episode, such as Sherlock and Moriarty's confrontation at Reichenbach Falls (which was part of Sherlock's mind palace). The final episode of series 4 "The Final Problem" is named after this story.