The Line Separating Horror and Mystery Fiction
There is a nearly continuous spectrum of fictional deviance, in which such melodramatically exaggerated antagonists as Arthur Conan Doyle’s Professor Moriarty, Sax Rohmer’s Fu Manchu, and Thomas Harris’s Hannibal Lecter are not far removed from such prototypical horror fiction adversaries as Clemence Housman’s The Were-wolf (1896), Richard Marsh’s The Beetle (1897) and Bram Stoker’s Dracula (1897). However, one very significant difference between the two genres has resulted in the drawing of clear line between them in terms of their historical development and readership.
When a detective’s use of logic eventually leads to an unassailable conclusion as to the identity of a perpetrator, he or she usually has an established legal apparatus to bring to bear on the apprehension, conviction, and punishment of the offender. Should that fail—as it often does in tales of crime-fighting that take a cynical view of the law’s efficacy—the detective can fall back on some other practical means of retribution (usually a gun). By contrast, in a horror novel, the conclusion to which a protagonist’s logic leads is an arbitrary contrivance of the author, and so is any means of exorcism by which normality can be restored. The law cannot cope with the supernatural, and guns are impotent to dispel it.
This discrepancy is so considerable as to create awkward difficulties for any narrative that attempts to straddle the line separating the horror and mystery genres, in spite of the fact that much horror fiction is, structurally speaking, a subspecies of mystery fiction, and the fact that much naturalistic mystery fiction also finds opportunities to deploy an exploit an element of horror.