The tone of "The Adventure of the Speckled Band" is mysterious and suspenseful, while also filled with admiration for the capacities of the human intellect. First, Doyle uses Watson's narration to generate suspense. From the beginning of the story, Watson's language emphasizes the reader's lack of knowledge about the mysterious events surrounding the Roylotts of Stoke Moran. This is evident in his introduction to the story:
It is possible that I might have [the events in question] upon record before, but a promise of secrecy was made at the time, from which I have only been freed during the last month by the untimely death of the lady to whom the pledge was given. It is perhaps as well that the facts should now come to light, for I have reasons to know that there are widespread rumours as to the death of Dr. Grimesby Roylott which tend to make the matter even more terrible than the truth.
By noting that the events surrounding the mysterious, unnamed lady have long been kept secret, as well as dismissing any rumors about Dr. Grimesby Roylott's death as exaggerated, Watson implies that his forthcoming account is the exclusive source of the facts of the crime. This means, moreover, that the reader is the first to gain access to these facts. Watson's passing comment that the Roylotts are a "well-known Surrey family" further suggests that his account of the crime is highly coveted information. In this way, Doyle skillfully builds the reader's anticipation for the truths the story will reveal about the crime.
It is also important to note that, because Watson narrates the story in the first person, the tone provides crucial insight into characterization. In particular, Watson's narration is filled with admiration for Sherlock's deductive abilities. While describing his enthusiasm for joining Sherlock in solving his cases, Watson says:
I had no keener pleasure than in following Holmes in his professional investigations, and 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.
Watson's tone here is fond and effusive in its praise for Sherlock. In this way, the tone of the story contributes to the reader's understanding of Sherlock's formidable intellect. As an example of detective fiction, the story is as invested in illustrating the brilliance of its central detective as it is in elucidating the crime he solves. This focus is in keeping with the Victorian era's fascination with science and the potential of human intelligence and innovation to improve society.
