Dr. Henry Jekyll, a reputed physician, becomes conscious of the duality, the mixed good and evil, in his nature. On the one hand, he is a doctor who has made a name for himself by a rigorous devotion to his discipline, and besides, has a solid reputation for the generosity of his impulses; on the other, he has always had a secret passion for self-indulgence, for enjoying himself in several dark ways by throwing off all restrain. He comes to discover a drug by means of which he can transform himself into another personality to be known as Mr. Hyde who absorbs all the evil instinct of the doctor. As Mr. Hyde, Dr. Jekyll gives free rein to all his secret impulses. The discovery of the drug enables Dr. Jekyll to change himself at will and indulge his evil self.
Once in the course of his nocturnal escapades, Mr. Hyde brutally kills an eminent public man called Sir Danvers Carew. This murder gives rise to a public scandal and a great public commotion. The culprit remains untraced, the commotion subsides and Mr. Hyde is not heard of for quite a while. Now the too frequent administration of the drug makes it less and less effacious and the evil aspect of Dr. Jekyll gradually acquires an ascendancy over his good. Once he found himself suddenly transformed into Mr. Hyde when he had no means of entering his laboratory. It was only through the good offices of his friend, Dr. Lanyon, a fellow doctor, that he was able to regain his original identity. The involuntary and unexpected transformation became increasingly frequent. Finally, one day, when the involuntary change took place, an ingredient of the drug had already run short and all his efforts of getting fresh supply failed. In terror and panic lest he should be discovered and arrested, he took his own life.
Mr. Utterson, the lawyer, is like the thread that connects all the episodes in the story; Dr. Jekyll, Dr. Lanyon and he have been great friends. He also has a friend in Mr. Enfield from whom he first learns about Mr. Hyde, the sinister figure. Mr. Hyde is mentioned in Dr. Jekyll’s will in a strange manner and the will is in Mr. Utterson’s custody. The language of the will and Mr. Enfield’s description of Mr. Hyde greatly disturbed Mr. Utterson and set him on his quest to have a direct knowledge of Mr. Hyde. Mr. Utterson is prompted in his quest by both suspicion about Hyde’s character and anxiety on account of his friend Dr. Jekyll. It is in the pursuit of that quest that he discovered Mr. Hyde one night and goes to Dr. Jekyll’s house to solve the mystery of the connection between Jekyll and Hyde. Dr. Jekyll’s reported absence, the subsequent gruesome murder of Sir Danvers’s Carew, Utterson’s visits to Jekyll, Dr. Lanyon’s disclosure about Jekyll, Utterson’s deepening suspicions and anxiety and the final visit to Dr. Jekyll’s house, where he breaks open the doctor’s laboratory door-well, Mr. Utterson’s association with all these incidents gives the story its coherence and its’ continuity.
One watches the skill with which Stevenson builds up the story and heightens the suspense. Indeed, it is all suspense packed. The intrigued and disturbed Mr. Utterson is driven on to solve the mystery of Hyde’s identity and his connection of Dr. Jekyll. The mystery is not solved until the end is reached. It is not only Mr. Utterson; the reader is equally intrigued and disturbed. He roused curiosity consumes him and he makes his way through the turns and twist of the story. The point to remember in this connection is that Stevenson is not dealing with a case of split personality. In the case of split personality, the appearance of a double or multiple personality is sudden, automatic, without and against the person’s will. In fact, the person concerned is a helpless victim of what comes about. There is a strange loss of memory separating the two or more identities of the same person. Moreover, the different identities of the individual have not always to do with the problem of good and evil.
Dr. Jekyll’s transformations are, to begin with, of his own making, though in course of time the change becomes involuntary, i.e. without any conscious effort on his part. He is no longer an agent but falls a panicked victim seeking restoration of his original self. Now there is a deep truth in this part of Stevenson’s portrayal of Jekyll’s career. Too much or too frequent indulgence of our baser nature serves to make it so powerful that it comes eventually to subordinate our higher nature. The evil triumph over the good. Thus Mr. Hyde is shown gradually to overthrow Dr. Jekyll. Dr Jekyll’s case is a pointer to what tragedy can overtake a man; however gifted he may be, when he chooses to divert his powers by pampering his secret, unlawful desires. The Satan in him grows too powerful to be mastered again. And here lies the universal and permanent human interest of the story that Stevenson relates so grippingly.