The tone in Part 1 of A Study in Scarlet is humorous, curious, and suspenseful. This first part of the novel is told from the first-person point of view of Dr. John Watson, and the narrative is supposed to be written in his journal. Watson has a sarcastic, wry sense of humor, which colors his narration in the first part of the novel. Although he eventually grows to like and admire Sherlock Holmes, he is initially skeptical about his new companion, finding him to be “conceited” and “bumptious.” He relays Holmes’s eccentric behavior when they first arrive at the scene of Enoch Drebber’s murder in humorous terms, highlighting the absurdity of his strange new friend’s behavior to the outside observer:
I had imagined that Sherlock Holmes would at once have hurried into the house and plunged into a study of the mystery. Nothing appeared to be further from his intention. With an air of nonchalance which, under the circumstances, seemed to me to border upon affectation, he lounged up and down the pavement, and gazed vacantly at the ground, the sky, the opposite houses […] Having finished this scrutiny, he proceeded slowly down the path.
Here, Watson rather sarcastically refers to Holmes’s apparent wandering nonchalance as a careful “scrutiny” of the scene and details the way that he “slowly” walks around looking at everything around him, even the sky, to emphasize how ridiculously cavalier he appears to be about the investigation. Watson also describes Holmes’s behavior as “border[ing] upon affectation,” which reveals that he still finds Holmes a bit pretentious and full of himself, even if he admires his intelligence.
The novel opens with a curious tone. Watson is fascinated by Holmes and intensely curious about his occupation, which his new friend remains oddly silent about. This curiosity builds in both Watson and Holmes as the novel goes on, and they uncover new clues while investigating Drebber’s murder. The novel builds a similar curiosity in the reader by incorporating a suspenseful tone. Because it is written from the first-person point of view of Watson, and because Holmes refuses to reveal any of his deductions until they’ve caught the murderer, the reader is left in the dark with Watson, wondering what Holmes must be thinking as he examines the evidence and “lounge[s] up and down the pavement” muttering to himself. As Doyle piles on more and more potential clues—a red candle, a body with no wound, a ring, blood on the floor, "RACHE" written in blood on the wall, mysterious pills, and so on—the suspense rises, and the reader is left wondering how all of the pieces must fit together.
In Part 2, which is narrated from a third-person omniscient point of view rather than the first-person perspective of Dr. Watson, the novel shifts into a more dramatic and sensational tone. The Utah landscape where this part of the story unfolds is depicted as dismal, dangerous, and inhospitable, representing Jefferson Hope’s negative perspective on Mormonism and his outlook about his own life—he has a deadly heart condition, and the woman he loved is dead, so he no longer cares if he lives or dies; all he cares about is revenge. Where Holmes is all logic, Hope is all emotion, and the comparatively emotional and sensational tone coloring his story reflects this.
