Sherlock Holmes must decipher a cryptic warning to prevent a murder, only to find himself entangled in a complex web of vengeance orchestrated by his nemesis, Professor Moriarty. Holmes and Dr. Watson receive a coded message that leads them to a country estate where a man has been killed under mysterious circumstances. The narrative shifts between the immediate investigation in England and a lengthy flashback detailing the victim's past in a violent American mining community. Holmes operates within the logical constraints of his deductive method, while the flashback reveals the brutal reality of the Scowrers, a secret society. The story is presented through a combination of third-person narration and a detailed written account of past events.

Readers frequently highlight the unique structure of this novel, which splits its focus between a traditional English mystery and a gritty American crime drama. Discussion often centers on the effectiveness of the flashback sequence in providing context for the central murder. Critics note that the book serves as a significant entry in the canon due to the direct involvement of Professor Moriarty. The pacing is often described as deliberate, shifting from the analytical environment of 221B Baker Street to the high-stakes environment of the American West. Many readers appreciate how the narrative expands the scope of the Holmesian world beyond the confines of London.