In Chapter 6, after Watson, Baskerville, and Mortimer pass through the tunnel and approach Baskerville Hall, Sir Henry’s fearful response is captured in a simile:
[Sir Henry] shuddered as he looked up the long, dark drive to where the house glimmered like a ghost at the farther end.
The scene’s overall setting and mood—the unruly, chaotic Moor with its Gothic tones and imagery—create a sense of foreboding and gloom. Once Baskerville Hall comes into view, Sir Henry has a visible reaction. Although he claims not to believe in the legend of the Hound, the sight of the house still frightens him. In comparing the house to a ghost, the story suggests it is part of the underworld, a place haunted by death and misfortune. According to the legend of the hound, Sir Henry is now in extreme danger.
Watson’s first impression of Baskerville Hall is “grim and grey.” Baskerville Hall represents a gateway between the aristocratic, orderly world of the Baskervilles in London and the chaotic wildness of the Moor. This wildness—primitiveness, even—infiltrates Baskerville Hall, filling it with ideas of ghosts and supernatural hounds. Sir Henry's reaction to the ghostlike house complements Watson's impression and foreshadows the (seemingly) supernatural elements to come.
In Chapter 6, after Watson learns the notorious convict Selden has escaped to the Moor, he uses a simile and compares him to a wild beast:
Somewhere there, on that desolate plain, was lurking this fiendish man, hiding in a burrow like a wild beast, his heart full of malignancy against the whole race which had cast him out.
Watson first describes the plain as a lonely, forlorn place where danger, like the presence of the escaped murderer Selden, awaits. In comparing Selden to a beast, the story suggests his crimes have transformed him from a human to a “primitive” animal. Because he has committed horrific crimes, Selden has been ousted by the community and is no longer welcome in society. Selden's sister and brother-in-law, Mr. and Mrs. Barrymore, provide him with food and clothing because Mrs. Barrymore feels responsible for him. Watson finds it shocking that Selden, “one of the most notorious criminals in the country,” is related to the respectable Mrs. Barrymore. Mrs. Barrymore attributes Selden’s ways to his spoiled upbringing—in other words, to poor nurture.
Through the case of Selden and Mrs. Barrymore, the story presents a stance on the debate over criminal nurture vs. criminal nature, whether or not behavior can be attributed to a predetermined biological source or is rather formed through one’s upbringing and history. Through the simile of the wild beast rejected by humanity, the story depicts criminality as the result of nurture and not inherent through nature.
In Chapter 9, Watson uses a simile to describe the escaped convict Selden before he evades capture from Watson and Sir Henry Baskerville:
The light beneath him was reflected in his small, cunning eyes, which peered fiercely to right and left through the darkness, like a crafty and savage animal who has heard the steps of the hunters.
Watson focuses on the quality of Selden’s eyes when describing him, which move quickly and appear intelligent. Yet Selden’s intelligence seems instinctual, more animal-like than human—his eyes are "small, cunning," like a creature that knows it's caught and is calculating its escape route. The use of the word "savage" and the reference to hunters also recall a more ancient, primitive, and perhaps even barbaric time befitting this remote, boggy setting. It is as if Watson and Baskerville are hunters in the wilderness, stalking Selden, their prey.
In comparing Selden to a “savage animal,” Watson also emphasizes the former’s criminal nature. This association of wildness and savagery with criminality connects to the novella's theme of nature versus nurture, though at this point, it's not yet clear whether the story argues that nature or nurture produces criminals. This simile does, however, make it clear that in the world of the story, criminality is savage and even subhuman.
Once Holmes confirms that Mr. Stapleton is Sir Henry Baskerville’s cousin and therefore an eligible heir, Holmes uses a simile that captures his wry enthusiasm:
We have him, Watson, we have him, and I dare swear that before tomorrow night he will be fluttering in our net as helpless as one of his own butterflies. A pin, a cork, and a card, and we add him to the Baker Street collection!
Holmes’s proclamation occurs at a crucial turning point in the plot. Holmes has revealed that Jack Stapleton is in fact related to Sir Charles and Sir Henry Baskerville. Stapleton’s father escaped to South America from England. He was believed to have died, but instead fathered Jack. This revelation importantly provides a motive for the murders. In comparing Stapleton to one of his captured butterflies, Holmes suggests they have solved the mystery, justice will be served, and the case will be added, like a pinned butterfly specimen, to Holmes’s collection of solved cases.
Holmes’s simile has an additional layer of meaning. As a trained entomologist and botanist, Stapleton uses his profession as an excuse to discover a safe path through the moors, where he hides the hound he uses to commit murder. But Holmes ultimately turns Stapleton's enthusiasm against him, making him the helpless butterfly.
In Chapter 14, as Watson, Holmes and Lestrade anxiously stake out the Stapleton house, the encroaching fog threatens to foil their plans to capture Stapleton once and for all. The story uses a simile to describe the menacing nature of the fog and surrounding landscape:
The fog-wreaths came crawling round both corners of the house and rolled slowly into one dense bank, on which the upper floor and the roof floated like a strange ship upon a shadowy sea.
The image of the fog is thick and murky. As the fog begins to overtake the house and surrounding area, the effect is so destabilizing that the surrounding moor appears to disappear, leaving the house only partially visible. This has an uncanny, nightmare-like effect, creating a sense of horror and disbelief that heightens the drama of the moment. Once again, the Moor is a site of the eerie and supernatural.
Importantly, the presence of the fog also threatens Holmes’s carefully-laid plans. The fog forces Holmes, Watson, and Lestrade to move away from the house. With Sir Henry out now of their sight, he is in even more danger. Eventually the fog makes it impossible for the trio to follow Jack Stapleton safely into the night, and they are forced to wait until morning.
