Sherlock Holmes is a fictional character of the late nineteenth and early twentieth centuries who first appeared in publication in 1887. He is the creation of British author and physician Sir Arthur Conan Doyle. A brilliant London-based "consulting detective", Holmes is famous for his intellectual prowess and is renowned for his skillful use of astute observation, deductive reasoning (though in reality, he uses abductive reasoning) and forensic skills to solve difficult cases.
Conan Doyle wrote four novels and fifty-six short stories that feature Holmes. The first story, A Study in Scarlet, appeared in Beeton's Christmas Annual in 1887 and Lippincott's Monthly Magazine in 1890, respectively. The character grew tremendously in popularity with the beginning of the first series of short stories in The Strand Magazine in 1891; further series of short stories and two serialised novels appeared until 1927. The stories cover a period from around 1875 up to 1907, with a final case in 1914.
All but four stories are narrated by Holmes' friend and biographer, Dr. John H. Watson, two are narrated by Holmes himself and two others are written in the third person. In two stories ("The Musgrave Ritual" and "The Adventure of the Gloria Scott"), Holmes tells Watson the main story from his memories, whereas Watson becomes the narrator of the frame story.
Conan Doyle said that the character of Holmes was inspired by Dr. Joseph Bell, for whom Doyle had worked as a clerk at the Edinburgh Royal Infirmary. Like Holmes, Bell was noted for drawing large conclusions from the smallest observations.[1]

Episode I:

Holmes is called upon by a masked gentleman introducing himself as Count Von Kramm, an agent for a wealthy client, but Holmes quickly deduces that he is in fact Wilhelm Gottsreich Sigismond von Ormstein, Grand Duke of Cassel-Felstein, the hereditary King of Bohemia. The King admits this, tearing off his mask.
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Holmes, Watson and the king of Bohemia.
It transpires that the King is engaged to Clotilde Lothman von Saxe-Meningen, a young Scandinavian princess, but the King's in-laws-to-be would have a very low opinion of him if any evidence of his former liaison with an opera singer named Irene Adler, originally from New Jersey, were ever revealed to them. Unfortunately, that is what the lady herself is threatening to do, apparently not, though, for monetary gain, for the King's agents have already tried to buy the evidence. They have also broken into Miss Adler's house to try to find it.
It is a photograph described to Holmes as a cabinet (5 1/2 by 4 inches), and therefore too bulky for a lady to carry upon her person, showing both the King (then the Crown Prince), and Irene Adler. The King gives Holmes £1,000 to cover any expenses. Holmes asks Dr. Watson to join him at 221B Baker Street at 3 o'clock the following afternoon.
The next morning, Holmes goes out to Miss Adler's house dressed as an out-of-work groom and manages to elicit useful information from the other stable workers. Irene Adler has a gentleman friend Godfrey Norton, a lawyer, who calls at least once a day. On this particular day, Norton comes to visit Miss Adler, and soon afterwards, takes a cab to the Church of St. Monica in Edgware Road. Minutes later, the lady herself gets in her landau bound for the same place. Holmes follows in a cab and, arriving, finds himself dragged into the church to be a witness to Godfrey Norton's and Irene Adler's wedding. Curiously, they go their separate ways after the ceremony.
Holmes decides to make his move that evening, with Watson's help. Disguising himself as a simple-minded clergyman, he arrives at Irene Adler's house and, with his agents' help, causes a commotion in which he falls down with his face bloodied, just as Miss Adler, or Mrs. Norton, arrives home. She has the clergyman conveyed into the house where she tends to him. Watson, having been instructed to keep near the sitting room window, waits for Holmes to raise his hand. At this signal, Watson throws a plumber's rocket through the window and yells "Fire!", as do the assorted other characters in the street, hired by Holmes with the money from the King. Holmes observes Mrs. Norton rushing to a panel in the sitting room, opening it, and beginning to take something out. Having thus discovered where the photograph is, Holmes calls out that it is a false alarm, and contrives to leave the house and meet Watson at the corner as prearranged.
Upon arriving back at Baker Street, however, something odd happens: they hear a voice say "Good-night, Mister Sherlock Holmes". Holmes recognizes the voice but cannot place it. If he could, he would deduce what the episode meant.
Holmes, Watson, and the King go to Irene Adler's house early the next morning to see about achieving what Holmes did not have the opportunity to do the night before, namely stealing the photograph. However, they find that she and her husband have left England, never to return. The picture is gone, and in its stead another has been left, showing only her.
She has also left a letter for Holmes, making it plain that she knew who he was – her suspicions were aroused by the "fire" – and that he was likely to have been hired by the King. She declares that she loves and is loved by Godfrey Norton and no longer feels the need to mire her former lover in scandal, and also that the King need never worry now about the photograph – unless he is foolish enough to take any threatening action against her. She has, of course, kept it. She also reveals that she followed him home after the fire and she was the one that said "goodnight" to him.
The king is satisfied with this outcome, and offers a valuable ring to Holmes as his reward. Holmes, however, is impressed by the intelligence of Irene, and asks instead to keep her portrait. Later Holmes receives a gold snuff box from the King.