Sherlock Holmes, the story’s protagonist, demonstrates the traits traditionally seen in detectives, including a superhuman intellect, a focus on logic and rational thinking, and an eccentric personality. Early on, Watson praises his friend’s genius by stating that he has “no keener pleasure than in […] admiring the rapid deductions, as swift as intuitions, and yet always founded on a logical basis with which he unravelled the problems which were submitted to him” (142). Holmes demonstrates these remarkable mental powers by deducing the mode of transportation Helen used from the mud stains on her sleeve. Like Edgar Allan Poe’s C. Auguste Dupin before him, Holmes is also an eccentric. He pursues the investigation at Stoke Moran with frenetic energy: During his inspection of Julia’s room, he “threw himself down upon his face with his lens in his hand and crawled swiftly backward and forward, examining minutely the cracks between the boards” (151). Even when examining the scene of a terrible crime, he cannot hide how much he relishes his work. As the protagonist, Holmes’s decisions and detective skills shape the story.

However, Doyle adds depth to his protagonist’s personality and shows him to be more than a perfect calculating machine.