In London, Gabriel John Utterson, a prosecutor, is on his weekly walk with his relative Richard Enfield, who proceeds to tell him of an encounter he had seen some months ago while coming home late at night from Cavendish Place. The tale describes a sinister figure named Edward Hyde who tramples a young girl, disappears into a door on the street, and re-emerges to pay off her relatives with 10 pounds in gold and a cheque signed by respectable gentleman Dr. Henry Jekyll (a client and friend of Utterson's) for 90 pounds. Jekyll had recently and suddenly changed his will to make Hyde the sole beneficiary. This development concerns and disturbs Utterson, who makes an effort to seek out Hyde. Utterson fears that Hyde is blackmailing Jekyll for his money. Upon finally managing to encounter Hyde, Hyde's ugliness, as if deformed, amazes Utterson. Although Utterson cannot say exactly how or why, Hyde provokes an instinctive feeling of revulsion in him. Much to Utterson's surprise, Hyde willingly offers Utterson his address. After one of Jekyll's dinner parties, Utterson stays behind to discuss the matter of Hyde with Jekyll. Utterson notices Jekyll turning pale, yet he assures Utterson that everything involving Hyde is in order and that he is to be left alone. A year passes uneventfully. One night, a servant girl witnesses Hyde beat a man to death with a heavy cane. The victim was MPSir Danvers Carew, who was also Utterson's client. The police, who suspect Hyde, contact Utterson. He leads the officers to Hyde's apartment, feeling a sense of foreboding amid the eerie weather (the morning is dark and wreathed in fog). When they arrive at the apartment, the murderer has vanished, but they find half of the cane (described as being made of a strong wood but broken due to the beating) left behind a door. It is revealed to have been given to Jekyll by Utterson. Shortly thereafter, Utterson again visits Jekyll, who now claims to have ended all relations with Hyde. Jekyll shows Utterson a note, allegedly written to Jekyll by Hyde, apologizing for the trouble that he has caused him and saying goodbye. That night, however, Utterson's clerk points out that Hyde's handwriting bears a remarkable similarity to Jekyll's own. For a few months, Jekyll reverts to his former friendly and sociable manner, as if a weight has been lifted from his shoulders. Later, Jekyll suddenly starts refusing visitors, and Dr. Hastie Lanyon, a mutual acquaintance of Jekyll and Utterson, dies suddenly of shock after receiving information relating to Jekyll. Before his death, Lanyon gives Utterson a letter, with instructions that he should only open it after Jekyll's death or his disappearance. Utterson goes out walking with Enfield, and they see Jekyll at a window of his laboratory. The three men start conversing, but a look of horror suddenly comes over Jekyll's face, and he slams the window and disappears. Soon afterwards, Jekyll's butler, Mr. Poole, visits Utterson in a state of desperation and explains that Jekyll has secluded himself in his laboratory for several weeks. Utterson and Poole travel to Jekyll's house through empty, windswept, sinister streets. Once there, they find the servants huddled together in fear. They go to see the laboratory where they hear that the voice coming from inside is not the voice of Jekyll and the footsteps are light and not the heavy footsteps of the doctor. After arguing for a time, the two of them resolve to break into Jekyll's laboratory. Inside, they find the body of Hyde wearing Jekyll's clothes and apparently dead from suicide. They find also a letter from Jekyll to Utterson promising to explain the entire mystery. Utterson takes the document home, where he first reads Lanyon's letter and then Jekyll's. The first reveals that Lanyon's deterioration and eventual death resulted from the shock of seeing Hyde drinking a serum, or potion, and as a result of doing so, turning into Dr. Jekyll. The second letter explains that Jekyll, seeking to separate his good side from his darker impulses, discovered a way to transform himself periodically into a creature free of conscience, this being Hyde. The transformation was incomplete, however, in that it created a second, evil identity, but did not make the first identity purely good. At first, Jekyll reports that he delighted in becoming Hyde and rejoiced in the moral freedom that the creature possessed. Eventually, however, he found that he was turning into Hyde involuntarily in his sleep, even without taking the potion... (Excerpt from Wikipedia)