Many reviews describe this as a horror novel, but I'd classify it as a suspense thriller. If you've seen the movies "The Happening" or "Pitch Black," it's a very similar premise, set in the context of a post-apocalyptic survivor drama. While the themes might not be too original, it was a very entertaining read with well-drawn characters that I'd recommend, but with the caveat that animals do come to harm in the story (although the descriptions aren't overly graphic).