While scrolling through the (hundreds of) posts in my RSS reader the other day, my eyes idly passed by an article, I think it was on one of the Guardian blogs, that opined that the boundaries between crime fiction and horror are now so blurred that they are pretty much one and the same. I wanted to write a post disagreeing, of course, but I haven't been able to track down the original article. So instead of disagreeing with the specific article, I'll disagree with the premise.
Books that are said to blur the distinction between horror and crime fiction are, for example, American Psycho by Brett Easton Ellis, Let the Right One In by John Ajvide Lindqvist and almost anything by Stephen King. I haven't read either of the former two books, and have not read any Stephen King for years, until I attempted to read "Cell" over Christmas (a book I bought purely on the strength of its title, but it turned out to be about phones not biology). I didn't get very far with it, as it was a series of set pieces describing deaths in nauseating detail, with practically no plot (such as it was, the plot was done much better in the same author's The Stand many years ago).
I don't read the horror genre, but looking at the best selling "crime" novels, one sees books that dwell on the minutiae of dead bodies, ancient dead bodies, deformities, torture by, respectively, Patricia Cornwell, Kathy Reichs, Mo Hayder and Karin Slaughter. Whether one would call these in any sense "horror" novels, rather than an excessive interest in decay and pain, I don't know. I don't think I would.
The best-selling crime novelists in the world are, to my knowledge, James Patterson, Dan Brown and John Grisham. James Patterson writes fairly up-front violence as part of his plots, but in a comic-book sense. Dan Brown writes conventional action thrillers with a religious/symbolic element. John Grisham mainly writes legal, courtroom-style dramas. No horror there, then.
The best-selling crime authors in the UK are Ian Rankin and Val McDermid. The former writes conventional police procedural detective stories, and the latter, although she has flirted with the torture-porn genre, has moved away from that in the past few years and now writes books without that element (her initial Tony Hill novels were quite gruesome, but no longer are).
People who read crime fiction regularly will be familiar with Michael Connelly, Robert Crais, Harlan Coben, Martin Edwards, Ann Cleeves, Peter James, Peter Robinson, Janet Evanovich, George Pelecanos, Susan Hill, Jonathan and Faye Kellerman, Sue Grafton, J. D. Robb, Linwood Barclay, Mary Higgins Clark and many other top-selling novelists. One thing all these writers have in common is that their books are based on plot, not on gruesome grisle: their appeal lies in the fact that they tell a good story - sometimes dark, sometimes not – about interesting characters.
Moving to mainland Europe, the most popular authors at the moment include Andrea Camilleri, Henning Mankell, Karin Fossum, Jo Nesbo, Stieg Larsson, Arnaldur Indridason and Camilla Lackberg. No "blurring of the horror boundaries" in any of these novelists' work – although Jo Nesbo does like his set-pieces of baroque violence, these are limited to a (skippable) few pages in each tome, the vast majority of each being a traditional police-procedural story.
Of course I have missed out many examples here. I have also ignored some authors who do write visceral books, eg Stuart MacBride, Simon Beckett or Mark Billingham, or who like to describe lots of violence in the form of fights, shoot-outs, etc (I can't give many examples as I don't read many in this subgenre). However, a fascination with violence is not the same as horror.
To my mind, "horror" involves the supernatural in some sense – the book is about events that can't be explained. This genre goes back to Edgar Allen Poe, Henry James and stretches to James Herbert, Clive Barker and many others of whom I've never heard – culminating in the current teenage vampire fad (soon to be replaced by angels and dogs I gather) represented by Stephanie Meyer and countless other similar authors. Crime fiction, on the other hand, is about a plausible, real-world story, perhaps not explained but certainly explainable. Perhaps an analogy is the difference between "science in fiction" (Arrowsmith, Intuition) and "science fiction" (Foundation, Contact, Dune). In my mind, therefore, if it's about ghosts, vampires and other impossible constructs, it isn't crime fiction.