At first, Arthur Charpentier, whose mother keeps the boardinghouse, is suspected of the murder; Drebber had made unwanted advances at Arthur’s sister and had made himself a very unpleasant boarder. But then, Stangerson, too, is killed, and it soon becomes clear that the two deaths are linked. Since Arthur Charpentier was in police custody at the time of the murder, there’s no way he could have committed the crime. Another theory of Drebber’s murder is that Stangerson committed it; that theory, too, is scuttled by Stangerson’s murder.

Holmes puts his deductive powers to work and figures out who killed Enoch Drebber and Josepth Stangerson. It turns out that their murders are linked to events in their pasts. You might even say that their pasts catch up with them.

Several important elements run through this novel. One of the most important, from the perspective of crime fiction, is Holmes’ approach to solving crimes. Arthur Conan Doyle has said that fictional detectives of his day came to their conclusions almost miraculously. Conan Doyle wanted a detective who solved crimes and came to conclusions through scientific means. He succeeded. Throughout the novel, we see this kind of deduction based purely on Holmes’ observations and his reasoning from what he has seen and heard. This was innovative, and criminal investigation has used this kind of logic since then. As a matter of fact, crime scene units still provide this kind of evidence and detectives still use it.

Another element that runs through this novel is the set of characters who later become integral to the Holmes stories. There are Holmes himself and Watson; this novel introduces both characters and gives us backstory for each. There are also the London detectives Lestrade and Gregson, whom Holmes describes as “…the pick of a bad lot.”

There are also the Baker Street Irregulars, a group of young boys led by the eldest, Wiggins, who reports directly to Holmes. These boys know the city very well, since they basically live in its streets. They see everything that happens and what they don’t see, they often can find out without calling attention to themselves. All of these characters add interest and depth to the Holmes stories, and they all play roles in this one.And then there’s London itself, which, cliché as it may seem to say so, really does become an important character in this novel (although interestingly enough, about half of the action doesn’t take place there). Conan Doyle describes the city’s alleys, neighourhoods, major streets and landmarks vividly, so that the reader feels a strong sense of place. We also see the element of the past affecting the present. That plot point’s been used in a lot of crime fiction since A Study in Scarlet, and it’s an effective device in this novel. Once Holmes deduces who the murderer of Drebber and Stangerson is, he tricks the killer into a meeting and once the killer is caught, we learn what the motive for the murders is. It turns out that Drebber and Stangerson are hiding something in their pasts. Someone bent on revenge knows what that secret is and is determined to right a terrible wrong.Because the plot depends a great deal on events from the past, we also see an element of flashback. Most of Part II of the novel, in fact, is a long flashback that tells the story of Drebber and Stangerson and explains why the killer is determined to get revenge.Holmes’ detection methods, his eccentric character and the other “regulars” in the Holmes stories are introduced in this novel. So is Holmes’ London. All of these elements combine with the element of the past’s effect on the present to create this case of two murders.

Review by Margot Kinberg, Confessions of a Mystery Writer