A frequent theme is to match Holmes with other literary characters, and by now he has met everyone from Dracula to Father Brown who might conceivably have overlapped his life. I was intrigued by John R. King's novel, "The Shadow of Reichenbach Falls" for this reason. While King explores where many have gone before-the lost time after Reichenbach-he uniquely involves William Hope Hodgson's "Carnacki the Ghost-Finder," a character that hasn't shown up much anywhere besides in Hodgson's largely out-of-print stories and a few horror/Lovecraft crossovers since.
Carnacki was one of the first of the "mystic detectives" school, followed by such characters as Jules De Grandin and John Silence, but was unique for the very modern "scientific" approach (for the time) he took to his work. The "electric pentacle" (which I always visualized as a sort of neon construction) was Hodgson's invention and figures in many of his stories.
Unfortunately, given a potentially promising premise, King's book falls into the disappointing/mildly entertaining category, having a rather poorly conceived opening. King does not manage to capture either Carnacki or Holmes' voice convincingly. The heroes' escape from Reichenbach on foot across a glacier-ridden mountain pass is implausible given the terrain: there is a glacier at the head of the valley in which the Falls are found, but it is far in the other direction that the action goes, and there is no pass there. Also, their pursuer lets off several rifle shots, which Watson could not have failed to hear.
From this point the book begins to show some gleams of inspiration, as King takes on the formidable tasks of providing origin stories for both Carnacki and for Moriarty. The latter is best done, explaining how Moriarty becomes the lord of crime in England by applying what I might call "the calculus of crime."
The dénouement is rather better than the beginning, although not, in my mind, entirely satisfactory. There are nice touches, such as the rational Holmes and the mystical Carnacki disagreeing as to whether anything supernatural actually occurred. An amusing light read for fans of the genre.