The Sherlock Holmes stories are a classic—and even foundational—example of the mystery genre. Specifically, "The Adventure of the Speckled Band," along with the other stories in Doyle's collection, is an example of detective fiction, which was popularized in the English-speaking world in the 19th century. Stories of this genre share a now-familiar structure: they present a mystery surrounding a crime, then follow a detective's investigation until the crime is solved at the end of the story.
In accordance with this structure, "The Adventure of the Speckled Band" begins by presenting the reader with the central mystery: how did Dr. Grimesby Roylott murder his daughter? Helen's visit to Sherlock's office, during which she describes at length her recollections of her sister's death, provides a convenient means by which to present these facts to the reader. Then, Sherlock and Watson visit the crime scene in search of more information that will allow them to answer the central question. This information is also offered to the reader, which invites the reader to attempt to solve the mystery along with the protagonist detective. Finally, Sherlock solves the mystery and explains the brilliant deductions he made from limited facts in order to reach his conclusions.
