On the night of January 9, Lanyon writes, I received a registered letter. Immediately, I recognized the handwriting of my old school-companion Henry Jekyll on the envelope. This surprised me. Henry and I weren't in the habit of corresponding; after all, we both live in London and I had just seen him the night before at one of his dinner parties. Whatever could be the reason for such a formality as sending a registered letter? My curiosity was high.
Dear Lanyon [writes Jekyll],
Despite the fact that we have differed on scientific matters in the past, you are one of my oldest friends, and that is why I am asking you to do a favor for me. It is a favor on which my honor rests. If you fail me, I am lost.
Please help me. Take a cab to my house, Poole will let you in, and then go to my room. If the door is locked, force it open. Open the drawer marked "E" (force the lock if necessary), and take out all its contents — some powders, a vial, and a paper book. Take everything home with you. Then, at midnight, a man will arrive at your house, ordered to do so by me. Give him the drawer you took from my room. That is all. If you do this, you will have earned my complete gratitude. I know that what I am asking borders on the fantastic, but if you fail to carry it out, either my death or my madness will be on your conscience. I tremble at the thought that you might fail me. If you do this, however, my troubles will be over.
P.S. If the post office fails to deliver this on schedule, do as I ask anyway. Expect my messenger at midnight. It may be too late; I cannot say. If it is, you will have seen the last of Henry Jekyll.
After I finished reading Jekyll's letter, I reflected on the possibility that Dr. Jekyll was insane. Yet until that was proved, I felt bound to do what my old friend asked me to do. Thus, I went immediately to Jekyll's house; a locksmith had been called and after two hours, the door to Jekyll's private study was opened. I took out the drawer described in Jekyll's letter, tied it carefully in a sheet, and returned home with it. There, I examined it carefully. What I found whetted my curiosity, but it told me little that was definite. There was a simple-looking sort of salt, a vial half-full of blood-red, highly pungent liquor, and the notebook contained little — a series of dates, covering a period of many years, which ceased quite abruptly nearly a year go. A few brief remarks were beside the dates; the word "double" occurred perhaps six times in a total of several hundred entries and once, very early in the list, were the words, "total failure," followed by several exclamation marks. For the life of me, I couldn't imagine how any of this could affect the honor, the sanity, or the life of my old friend Dr. Jekyll. And why all the secrecy? The more I thought about it, I wondered if Jekyll might not be suffering from some sort of cerebral disease. Yet I was determined to do as he asked — but not before loading my old revolver.
At midnight, the knocker on my door sounded very gently. Outside was a small man crouching against one of the porch pillars. I asked him if he was Jekyll's agent. He gestured a tortured "yes" and, looking furtively behind him, slipped inside. Keeping a hand on my revolver, I took a close look at the small man. I had never seen him before. He was certainly a distasteful creature; his face jerked in convulsions, he seemed physically ill, and as a doctor, I wondered about these symptoms. His clothes, which were obviously expensive, were much too large for him. His trousers were rolled up ridiculously, and the waist of his coat fell below his hips. Under other circumstances, I would have laughed at his clown-like appearance, but this man was clearly abnormal, disgustingly so. Again, as a medical man, I couldn't help being curious about his origin, his life, and his livelihood.
The strange little man was unusually excited, asking again and again if I had "it." I tried to calm him, but he seemed to be on the verge of hysteria, so I pointed to where it lay, on the floor behind a table. Instantly, he sprang on it, then laid his hand on his heart, and I could hear his teeth grate and his jaws convulse. Then he began mixing the powders with the liquid, which changed colors before my eyes. I was fascinated, and he noted this and asked, "Will you be wise? Will you be guided? I can take this glass and leave. Or I can swallow it before you and show you a new land of knowledge, new paths to fame. What you see will stagger the Devil himself."
I confess that my curiosity again got the best of me. I asked him to continue. He agreed but reminded me of my professional vows and of my deep-rooted belief in traditional medicine, for what I was about to see would be a wonder from the realm of transcendental medicine.
Then he drank the potion in one long swallow and cried out, reeled, staggered, clutched at the table, and suddenly his face became black, his features began to melt, and in the next moment, Henry Jekyll stood before me.
What he told me during the next hour, I cannot bring myself to put on paper. I can only relate what I saw and how my soul was sickened. I ask myself if I believe it, and I cannot answer. Terror haunts me constantly. My faith in medicine and mankind has been sundered. I feel my days are numbered. Only one thing remains to be said. That "creature" who came on an errand for Jekyll, by Jekyll's own admission, was none other than Edward Hyde, the murderer of Sir Danvers Carew!
In terms of the narrative structure of the novel, finally and for the first time, the reader comes to the astounding realization that (1) Dr. Jekyll and Mr. Hyde are one and the same person; or (2) Dr. Jekyll and Mr. Hyde are two parts of the same person, one evil and the other good; or (3) Mr. Hyde is a part of Dr. Jekyll, that diminished part that represents the evil in all of us. There could be other options in addition to the above, but these are the most traditional.
Likewise, in terms of the narrative structure, this information comes to us in the form of a long narrative set forth by Dr. Lanyon, but we should also be aware that Dr. Lanyon does not tell us everything: When Hyde has drunk the potion and has again become Jekyll, the two "old friends" apparently talked for an hour, but Dr. Lanyon writes, "What he [Jekyll] told me in the next hour, I cannot bring my mind to set on paper." Therefore, the reader does not yet have the complete story, because the timid, shocked, and horrified Dr. Lanyon is too stricken by the implications of Jekyll's story to even write it down.
We should remember from Chapter 6 that on the 8th of January, Lanyon, along with Utterson and others, dined at Dr. Jekyll's house; then on the 9th of January, Dr. Lanyon received the note from Dr. Jekyll (dated the 10th of December, an error of consistency on Stevenson's part), a note in which Jekyll, in the person of Hyde, pleads with his old friend for help; now we realize this will be a type of help which will finally bring Lanyon into direct contact with Jekyll's theories, which Lanyon has so long rejected. The direct confrontation will be in the person of Edward Hyde, with his sinister and evil ways. And true to form, Lanyon's initial reaction to Hyde is the same as the reaction of others — "There was something abnormal and misbegotten in the very essence of the creature."
When Hyde has received the chemicals from Dr. Lanyon and has mixed the infamous potion, he taunts Lanyon with a challenge: Shall he (Hyde) leave now, with Lanyon still in ignorance, or does Lanyon have "the greed of curiosity?" If Hyde stays, then "a new province of knowledge and new avenues to fame and power shall be laid open to you, here, in this room, upon the instant; and your sight shall be blasted by a prodigy to stagger the unbelief of Satan." We must first question how this revelation will open up new avenues of "fame and power" to Lanyon — especially since the same knowledge has destroyed Jekyll. But we must remember that it is not Jekyll who is offering Lanyon this awful challenge — it is, ironically, Hyde, and he wants revenge for the many times that Lanyon has ridiculed Jekyll for being "too fanciful" and "too metaphysical" and for being interested in such "unscientific balderdash." Finally, Lanyon is to see with his own eyes what he has so long rejected and ridiculed. The entire person of Jekyll/Hyde would, of course, not taunt the good Dr. Lanyon, but the evil, malicious, and vindictive Hyde takes great, perverse pleasure in taunting Lanyon.
Lanyon assents, and Hyde drinks the potion. What happens to Hyde is a delightful challenge to filmmakers and is vividly described by Stevenson: "A cry followed: he reeled, staggered, clutched at the table, and held on, staring with injected eyes, gasping with open mouth . . . He seemed to swell — his face became suddenly black and the features seem to melt and alter." The effect of this scene destroys Lanyon, for as we saw in Chapter 6, Dr. Lanyon is dead three weeks after this scene. Observing the metamorphosis, Lanyon can only scream, "Oh God . . . Oh God" again and again as he watches Hyde become Jekyll. Thus Hyde and, ultimately, Jekyll both have their revenge.
The horror of the transformation is not, we assume, the only thing that kills Lanyon. After the transformation, Jekyll talks to Lanyon for an hour, and we must assume that he tells Lanyon everything that we hear in Chapter 10. The point is that Lanyon cannot tolerate the idea that man has an evil nature, and yet he has just been exposed to the incontrovertible proof that man does indeed possess an actual evil nature which can be isolated from his dual-natured self. As we noted earlier, the actual horror of the discovery that Jekyll and Hyde are one and the same person lies not in the transformation itself but in the full realization concerning the nature of evil found in all men because Hyde has stood before Lanyon as EVIL INCARNATE. And this is followed by Jekyll's long explanation which Lanyon "cannot bring [his] mind to set on paper." For upon hearing Jekyll's story, Lanyon's "soul sickened . . . My life was shaken to its roots; sleep has left me; the deadliest terror sits by me at all hours . . . I feel that I must die." Thus, the deadliest terror that Lanyon fears must be the fear that his own evil nature will emerge, and for a prominent man who has lived an exemplary, mild, and meek life while attaining fame, this possibility is simply too much; it destroys him. But before it destroys him, he completely rejects not just Hyde, but Jekyll also — in his entirety. As Lanyon said in Chapter 6, "I wish to see or hear no more of Dr. Jekyll . . .
I am quite done with that person; and I beg that you will spare me any allusions to one whom I regard as dead." Thus, we now know that the horror of the discovery that Jekyll and Hyde are one person results in the discovery that Lanyon himself is also part evil. To escape thinking further about this self-realization, Lanyon therefore rejects Dr. Jekyll — as well as himself — because he has not the strength to struggle with evil. The knowledge of this phenomenon simply kills him.