Mc Murdo is a peculiar character.

In my opinion, the mystery surrounding McMurdo is what makes him peculiar, but more importantly, interesting. McMurdo is multi-dimensional and might even be considered three different characters in one person. He is first introduced as John Douglas, a faceless victim, and the object of Holmes’ investigation. We later learn, however, that Douglas is actually alive, and he commences to share his history, which comprises nearly the entirety of Part II. During this “story within a story," we learn that Douglas once bore the name “Jack McMurdo"..... that he was part of a notorious gang in the United States, which was not unlike the Mafia. At the end of Part II, we learn that “McMurdo” is really a Pinkerton detective named “Birdy Edwards." Throughout all three of his “identities," Douglas is described as fearless, intelligent, and good-humored. Douglas is an example of Conan Doyle’s skill as a writer, in that the reader is able to accept with little difficulty the composition of the “three-in-one” character.