Plot in The Adventure of the Speckled Band

Holmes likely solves the mystery in this moment of “reverie.” This pattern occurs in many Sherlock Holmes stories: Holmes pieces together a solution to the case before the story’s climax. In each story’s denouement, Holmes is already prepared with a lucid explanation. Holmes’s ability to crack the case before Watson and—in most cases—the reader is a large part of his mystique and appeal as a literary character.

The case is coming together for Holmes and the reader. Because this is a “locked room mystery,” Doyle is highlighting the details of the dummy bell-pull and the oddly-directed ventilation shaft—both keys to understanding how Helen’s sister was intruded upon and murdered. The tension tightens as the possibilities narrow.

One suspects this list—the pistol and the toothbrush—is meant to be a humorous touch. Spoiler: the toothbrush is never mentioned again in the story. Whether Holmes anticipated needing it is unclear. In retrospect, this looks like a joke.

By bringing Watson’s revolver into the narrative, Doyle evokes the dramatic principle of “Chekhov’s gun.” As Anton Chekhov famously wrote, “If you say in the first chapter that there is a rifle hanging on the wall, in the second or third chapter it absolutely must go off. If it's not going to be fired, it shouldn't be hanging there.” Look for the resolution to the tension of the revolver.

Though Helen shares this development in the third person, it is clear that Dr. Roylott is responsible for the repairs and for potentially sinister reasons. One wonders whether Doyle uses the passive voice here to throw the readers off Roylott’s trail.

First published in 1892, the events in “The Adventure of the Speckled Band” and Conan Doyle’s writing of it are close to contemporaneous. This time was the height of both the Victorian era in England and British rule over India, a fact important to the story’s plot.

The reappearance of Dr. Roylott at Stoke Moran reminds the readers of the danger he represents. The author brings Rollout back into the story to heighten the tension of the investigation.

Julia told her sister that she had been hearing a low whistling sound on several previous nights. On those nights the snake had been in the bed with her without her knowing it. On this last occasion she had evidently kept a match-box handy so that she could strike a light when she heard the whistle. In turning over in bed to reach for the matches, she must have rolled right on top of the snake and gotten bitten. This was the only time she actually saw the creature because it was the only time she had light.

This establishes that Julia was in a locked room just before her death. The biggest problem that Holmes has to deal with in this "locked room murder mystery" is how Julia Stoner could have been killed when she was in a room with the door locked and the window securely blocked by iron shutters.

The term "the speckled band" is used in the title and will be repeated several times throughout the story. The phrase will be one of the most important factors of the plot later on.

Dr. Roylott is the type of man who would make many enemies, including the local blacksmith, but they would all be afraid of him or his cheetah or baboon.

Dr. Roylott must have known that the snake would stay there because the weather was cold and the bed was the warmest place in the room. The text refers repeatedly to the unusually cold weather. It is early April when Helen Stoner comes to consult with Holmes, and it had been December when her sister Julia had become engaged.

Watson's presence is necessary for the possibility that there might be an encounter with Dr. Roylott, who would be quite capable of trying to harm both of them if he found them inside his home. Watson is carrying a revolver at the request of Holmes, and Roylott, like any typical country resident of the times, would surely have means of protection.

Recall Holmes’s theory that someone—presumably a gypsy—must have entered the bedroom through the window. It is noteworthy that Helen Stoner tells Holmes at the initial interview that Roylott was not merely tolerant of the gipsies but spent a great deal of time visiting them and traveling around with them. However, the bars over the window complicate Holmes’s theory.

It is Sherlock who rouses the snake's "temper." This indicates that Sherlock is responsible in some way for the death of Dr. Roylott.

Evidently Julia was trying to indicate that the "speckled band" had come from Dr. Roylott's room and that he was responsible for her dying condition. 

Doyle had Sherlock Holmes have an erroneous theory about the case so that the readers would remain in the dark until the true facts were revealed. Holmes explains to Watson that it was the discovery of the dummy bell-rope, the ventilator, and the fact that the bed had been fastened to the floor that made him change his theory. He says, "The idea of a snake instantly occurred to me.”

Holmes himself seems to be thinking that the gypsies must have been involved in Julia's death and that one of them is making the whistling sound in the early morning. Until Holmes and Watson arrive at Stoke Moran and are able to examine both Helen's and Dr. Roylott's bedrooms in person, this is the best working theory Holmes can develop.

This marks a shift away from Helen’s statement and into the actual investigation After this, the focus will be on Holmes and Watson.

The whole mystery turns on the problem of how Helen's sister could have been killed when she was "undoubtedly alone when she met her mysterious end." This aspect of the locked-room mystery proves most troubling for Holmes.

A trap was a light two-wheeled carriage with springs meant for traveling short distances. The railway system in England was excellent in those days, but getting from a station to a final local destination could be more difficult. Sometimes Holmes and Watson would have a driver sent to pick them up. Sometimes they would hire someone to drive them to wherever they were going and then leave them to find their own way back. They might even walk or hire horses at the livery stable and go on horseback. Sherlock Holmes frequently travels to outlying districts and seems to know all the train lines and even some of the timetables.