The third novel in Lois H. Gresh's Sherlock Holmes vs. Cthulhu series.

Now united, both Fitzgerald and Moriarty travel to Innsmouth, the stronghold of the cult of the Old Ones. Holmes and Watson, accompanied by Mycroft Holmes, follow them across the ocean and discover a structure designed to bring the Old Ones into the human sphere. Yet when it is destroyed people continue to mutate and go mad.