The setting and its significance in Part 1 Chapter 4

Watson picks up the narrative of the present day. White Mason is a friendly, quiet, but capable man. He meets Holmes, Watson, and MacDonald at Birlstone and helps everyone get settled, all the while talking about the case. He explains to Holmes how he checked the hammer that was found near the body (there was no evidence of it being involved in the crime) and the gun, which had the initials P, E, and N on it.