"The Adventure of the Three Gables" is one of the 56 Sherlock Holmes short stories by Sir Arthur Conan Doyle. It is collected in The Casebook of Sherlock Holmes and was first published in The Strand Magazine in October 1921 - April 1927.
The story begins with a visit to 221B Baker Street from Steve Dixie, a black man and a cowardly ruffian who warns Sherlock Holmes to keep away from Harrow. Watson has no idea what this dimwitted fellow is talking about, but Holmes knows who he is and what the intrusion is all about, and manages to elicit some interesting information from him, knowing that Dixie is easily imposed upon. Ironically, although Dixie has come to intimidate Holmes, Holmes cleverly secures Dixie's future cooperation by threatening to tell what he knows about the suspicious Perkins death involving Dixie. Dixie's boss is Barney Stockdale, and he must somehow be connected with the Harrow Weald case, of which Holmes has just learnt from a message from Mary Maberley, a lady who lives at Three Gables, a house at Harrow Weald.
Mrs Maberley is an elderly woman whose son, Douglas, has recently died in Rome, where he was an attaché. Some peculiar things have happened at Three Gables. Mrs Maberley has lived there nearly two years, and in all that time has attracted very little attention from her neighbours. Suddenly, however, a man came to her recently and offered to buy her house, despite several other similar nearby houses being empty and on the market. She was asked to name a price; so she named one £500 higher than what she had paid for it. The man readily agreed, and then asked to buy all the furniture in the house as well, which struck Mrs Maberley as very odd. She was not really willing to do it, and certainly not after her lawyer, Mr Sutro, told her that the legal agreement drawn up by this prospective buyer would forbid her to remove any possessions from the house when she moved out. Mrs Maberley finally decided that she did not like this business, and called the deal off.
As she is telling Holmes this story, he becomes aware that someone is eavesdropping on the conversation. He opens a door and drags in Susan, a wheezing maid. Through questioning and deduction, Holmes manages to establish that Susan communicated to Barney Stockdale the fact that her mistress was hiring Sherlock Holmes, and that, of course, precipitated Steve Dixie's visit. Holmes also finds out that it is a rich woman who has hired Barney Stockdale and his assorted thugs to do her dirty work. Susan is also a member of the gang, but will not give up all their secrets. She leaves in a huff.
Obviously, this woman, whoever she is, wants something in the house, and something that has come into the house quite recently. Mrs. Maberley cannot say what that might be, but Holmes, seeing some trunks with Italian placenames on them realises that her late son Douglas's belongings must hold the key. He instructs Mrs Maberley to try to get Mr Sutro to spend a couple of nights at Three Gables, to keep the house guarded. He also tells her to search through her son's belongings to see whether there is anything among them that could be of interest.
Holmes finds Dixie outside, keeping the house under surveillance. Dixie is now inclined to help Holmes if he can, to avoid any indiscreet talk about the Perkins lad who met his end so tragically. He swears, however, that he does not know who has hired Barney Stockdale.
Holmes goes to see Langdale Pike, a man who for years has made a living by being a gossipmonger for several publications. There is not one scandal in London that he does not know about, and as usual, he does not fail Holmes.
First, however, Holmes and Watson find themselves going back to Three Gables to investigate the burglary that has happened there. The burglars chloroformed Mrs Maberley, and stole a manuscript from her son's belongings. She managed to retain part of one sheet of paper from it when, coming round, she lunged after one of the thieves, who then shook her off.
The police inspector at the scene is treating the matter as an ordinary burglary, but Holmes knows better. He examines the bit of manuscript retained by Mrs Maberley, and it appears to be the end of a rather lurid novel. Holmes is struck by the peculiar wording; the story abruptly changes from third-person narration to first-person narration. It is in Douglas's handwriting; so it would seem that he was putting himself in a story that he was writing.
Holmes has now deduced everything.
He and Watson go to see Isadora Klein, a wealthy woman who is used to getting what she wants. At first they have a bit of trouble trying to see her; the footman will not let them in. However, they are speedily ushered into Mrs Klein's rooms once Holmes threatens to call the police and expose the whole sorry story.
The happenings at Three Gables and the information from Langdale Pike have all added up to something. It turns out that Douglas Maberley was ill-advised enough to be involved with Isadora Klein at one time. She broke the relationship off, and he almost wrought his revenge by writing a thinly-veiled account of their affair, to be published as a novel. Everyone in London would know who the characters truly were, were the novel ever published. Isadora managed to establish that no copy had ever been sent to Douglas's publisher, but realised that he must have a copy. Fearing that the scandal will end her engagement to the Duke of Lomond, she hired Barney Stockdale and his confederates to secure the manuscript. She tried legal means at first, and when that did not work, she resorted to crime. She has, of course, burnt the manuscript.
Holmes decides to force Mrs Klein to make amends for her wrongdoing without exposing her scandalous behavior to the police and in turn the public. He instructs Isadora Klein to write a cheque for £5000 to furnish Mrs Maberley with a first-class trip round the world, something she has always wanted, in return for his silence about Isadora's nefarious dealings.
Granada Television's series, featuring Jeremy Brett as Holmes and Edward Hardwicke as Dr Watson has faithfully presented the story with several differences. In the series, Douglas Maberley is depicted as Mary Maberley's grandson instead of her son as in the story. Furthermore, instead of dying in Rome, Douglas dies in his grandmother's house after a month of suffering from a bout of pneumonia caused by a savage beating he received from Mrs Klein's hired boxers. Langdale Pike is slightly more fleshed-out as a character. In a masquerade during the episode, Langdale Pike defines himself as the benevolent counterpart of Charles Augustus Milverton (the namesake of the story about a blackmailing antagonist) and points out that he suppresses more than he exposes. Pike is also mentioned in the radio adaptations of the Adventures of Sherlock Holmes, where his real identity is revealed. His name appears to be Clarence Gable, who adopted the sobriquet 'Langdale Pike' due to his seemingly immense height. Throughout the original story, Holmes seems to have acquired Steve Dixie's complete loyalty through blackmail. In the TV series, Dixie retains some enmity and during the break-in at the Three Gables, he ends up brawling with Dr Watson, severely beating him.