Although this novel is published as a supplement to the Arkham Horror games franchise, it only includes one Arkham Horror character, and that in a minor supporting role: Joe Diamond the P.I. The central characters of the novel are in fact historical figures: the young English WWI veteran Dennis Wheatley (prior to his days as an author) and escapologist Harry Houdini. Additionally, the screen actor Max Schreck has a part in the story, and it seems as though the meta-cinematic film Shadow of the Vampire (2000) had more than a little influence on the plot of the novel.

Despite the presence of Ramsey Campbell's ancient god Glaaki in the book's title, the god and its cult as represented here have little detail in common with "The Inhabitant of the Lake." Glaaki is still in a lake, but has been transposed from the Severn Valley in England to Dunwich, Massachusetts. The Dunwich setting notwithstanding, there are no explicit allusions to the events of Lovecraft's "Dunwich Horror," even when the investigators visit Professor Armitage at the Miskatonic University Library in Arkham.

The story uses many conventions of the murder mystery genre in addition to its horror elements, and these are fairly effective at moving the plot along. The disappearance of a movie actress and the murder of her replacement are--at first--the central subjects of investigation. What might have been a tame denouement in the final chapter pivots the focus back from mystery to horror.