Considered by turns part-gothic novel, part-psychological mystery, part-metafiction, part-satire, part-case study of totalitarian thought, it can also be thought of as an early example of modern crime fiction in which the story is told, for the most part, from the point of view of its criminal anti-hero. The action of the novel is located in a historically definable Scotland with accurately observed settings, and simultaneously implies a pseudo-Christian world of angels, devils, and demonic possession.