The scariest work of fiction I've read this year would be "Cat Out of Hell" by Lynne Truss, but my view seems to be a bit controversial.
Perhaps it was my imagination and experiences with death that did most of the work. A pit of corpses is not an abstraction in my mind. And the callous, detached yet methodic mannerisms of one of the characters reminded me of similar characters I myself had encountered out in the world.