There is no trace of Jekyll's corpse, which they expected to find. They note a mirror, and think it strange to find a mirror in a laboratory. Finally, they find a large envelope addressed to Utterson. It contains three smaller envelopes. The first is a will, much like the previous one, except that it replaces Hyde's name with Utterson's. The second is a note to Utterson, with the present day's date on it. Thus Utterson surmises that Jekyll is still alive. He takes the third envelope home to read carefully, promising to return that night and send for the police.

This chapter is a word-for-word transcription of the letter Lanyon sent to Utterson, one which he intended to be opened after Lanyon and Jekyll's deaths. Lanyon writes that after Jekyll's last dinner party, he received a letter from him. The letter asked Lanyon to go to Jekyll's home, remove a drawer from his lab, return with this drawer to his own home, and wait for a man who would come to claim it. The letter seems to have been written in a mood of desperation. Lanyon duly went to Jekyll's home, where he was met by Poole and a locksmith. They broke into the lab and Lanyon returned home with the drawer. Within the drawer, Lanyon finds several vials and a notebook recording years of experiments, but there is no hint of what the experiments involve. He waits for his visitor, increasingly certain that Jekyll must be insane. At the stroke of midnight, Mr. Hyde appears, to claim the drawer. Hyde is nervous and excited. He avoids polite conversation, intent on the contents of the drawer. In a burst of theatricality, Hyde asks Lanyon to witness something that he claims would stagger the unbelief of Satan. Taking up the vial, he tells Lanyon that his skepticism of transcendental medicine will now be disproved. Before Lanyon's eyes, the deformed man drinks the vial and turns into Dr. Jekyll. Lanyon here closes his narrative, stating that what Jekyll told him afterwards is too shocking to repeat.

This chapter is a transcription of the letter Jekyll left for Utterson in the laboratory. Jekyll writes how he was born to a large inheritance, a healthy body, and a hard-working, decent nature. His idealism allowed him to maintain a respectable seriousness in public while hiding his more frivolous and indecent side. By the time he was fully-grown, he found himself leading a dual life. When his scientific interests led to mystical studies in the divided nature of man, he hoped to find some solution. Jekyll insists that man is not truly one, but truly two. He dreamed of separating the good and evil natures within man. Jekyll eventually found a chemical solution that might accomplish just that. Buying a large quantity of salt as his last ingredient, he took the potion. At first, he experienced incredible pain and nausea. But as these symptoms subsided, he felt vigorous and was filled with recklessness and sensuality. He became the shrunken and deformed Mr. Hyde. He hypothesizes that because Hyde represented his evil side, which up to that point has been repressed, Hyde's stature was reduced. Upon first looking into the mirror, he is not repulsed by his new form but experiences a great thrill.

Jekyll was becoming too old to give exercise to his more embarrassing impulses, so transforming into Hyde was a welcome outlet. He thus furnished a home and bank account for his alter ego. Each time he transformed back into Jekyll, he felt wonder, not guilt, at Hyde's exploits. It was not until two months before the Carew murder that Jekyll found cause for concern. While asleep one night, he automatically transformed into Hyde. This convinced him that he must quit turning into Hyde, but after two months he caved in and took the potion again. The murder was the result of those two months of pent-up violence. Hyde was delighted with the murder, but even as he was transforming back into Jekyll, he knelt and prayed to God. Remorse, as well as relief at the impossibility of becoming Hyde, led to Jekyll's two months of healthy sociability and good intent. Eventually, Jekyll grew weary of constant virtue. Sitting in the park one day, he began to contemplate a return to such outlets for his desires as he had used before his experiments. But this failure of rigid mental control was enough to cause a spontaneous transformation into Hyde. He immediately felt braver but also hunted. It was that night that he sent word to Lanyon to get his potions for him. After that, he had to take a double dose of the potion every six hours to avoid spontaneous transformation into Hyde. Hyde grew stronger as Jekyll grew weak, and soon he ran low on the salt necessary for the potion. Jekyll used the last of the potion to buy time during which to compose this final letter.

Click here for part 1 of the summary of Dr. Jekyll and Mr. Hyde