Utterson is sufficiently convinced that he returns to Jekyll's house, where he and Poole break into the laboratory. There, they discover that the mysterious figure in the laboratory has just committed suicide by drinking a vial of poison. The body is that of Edward Hyde. They search the entire building for signs of Jekyll and can find nothing, except a note addressed to Utterson.
The note informs Utterson that he should go home and read, first, the letter from Dr. Lanyon and then the enclosed document, which is the "confession" of Dr. Henry Jekyll.
Dr. Lanyon's narrative reveals that Dr. Jekyll had written to him, in the name of their old friendship, and had requested him to follow precise instructions: go to Jekyll's laboratory, secure certain items, bring them back to his house, and at twelve o'clock that night, a person whom Lanyon would not recognize would call for these things. Lanyon writes that he followed the instructions precisely and at exactly twelve o'clock, a horribly disagreeable, misbegotten "creature" appeared at the laboratory to claim the items for Dr. Jekyll. Before leaving, he asked for a "graduated glass," proceeded to mix the powders and liquids, and then drank the potion. To Dr. Lanyon's horror, the figure transformed before his eyes into that of Dr. Henry Jekyll. Lanyon closes his letter by pointing out that the man who stepped into the house that night to claim Jekyll's items was the man known as Edward Hyde.
The final Chapter gives a fully detailed narration of Dr. Jekyll's double life. Jekyll had been born wealthy and had grown up handsome, honorable, and distinguished, and yet, he committed secret acts of which he was thoroughly ashamed; intellectually, he evaluated the differences between his private life and his public life and, ultimately, he became obsessed with the idea that at least two different entities, or perhaps even more, occupy a person's body. His reflections and his scientific knowledge led him to contemplate the possibility of scientifically isolating these two separate components. With this in mind, he began to experiment with various chemical combinations. Having ultimately compounded a certain mixture, he then drank it, and his body, under great pain, was transformed into an ugly, repugnant, repulsive "being," representing the "pure evil" that existed within him. Afterward, by drinking the same potion, he could then be transformed back into his original self.
His evil self became Edward Hyde, and in this disguise, he was able to practice whatever shameful depravities he wished, without feeling the shame that Dr. Jekyll would feel. Recognizing his two "selves," Jekyll felt the need of providing for, and protecting, Edward Hyde. Therefore, he furnished a house in Soho, hired a discreet and unscrupulous housekeeper, and announced to his servants that Mr. Hyde was to have full access and liberty of Jekyll's residence and, finally, he drew up a will leaving all of his inheritance to Edward Hyde. Thus, this double life continued until the murder of Sir Danvers Carew by Edward Hyde.
This horrible revelation caused Jekyll to make a serious attempt to cast off his evil side--that is, Edward Hyde--and for some time, he sought out the companionship of his old friends. However, the Edward Hyde side of his nature kept struggling to be recognized, and one sunny day while sitting in Regent's Park, he was suddenly transformed into Edward Hyde. It was at this time that he sought the help of his friend Dr. Lanyon. He hid in a hotel and wrote a letter asking Dr. Lanyon to go to the laboratory in his house and fetch certain drugs to Lanyon's house. There, Hyde drank the potion described in Lanyon's letter. The drug caused him to change to Dr. Jekyll, while Dr. Lanyon watched the transformation in utter horror.
After awhile, Edward Hyde almost totally occupied Jekyll's nature, and the original drug was no longer effective to return Hyde to Jekyll. After having Poole search throughout London for the necessary "powder," Jekyll realized that his original compound must have possessed some impurity which cannot now be duplicated. In despair at being forced to live the rest of his life as Hyde, he commits suicide at the moment that Utterson and Poole are breaking down the laboratory door.
