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.
