H.P. Lovecraft is possibly the most influential horror writer of all time, up there with the likes of Edgar Allen Poe. Countless other authors have used his work as a springboard, from the direct continuations of the Cthulhu Mythos by August Derleth, all the way through to the Dungeon Dimensions of Terry Pratchett's Discworld. There's scope for horror and comedy in his cosmic abominations, and Equoid is an excellent blend of the two.
Yes, it turns out that unicorns aren't beautiful, magical horses: they're actually the mind-controlling spawn of Shubb-Niggurath, and when fully grown they're as powerful as a tank and enjoy eating meat. We first learn about them from one of Lovecraft's "lost letters," in which he describes an encounter he once had with a unicorn as a young man. It's a note-perfect pastiche of his style, and Stross earns a lot of laughs by parodying Lovecraft's purple prose while also creating a pretty disturbing, at times nauseating, monster. Lots of little girls love unicorns, you see, so they're usually the first target for mind control.
For much of the story, it recalls Hot Fuzz more than anything else, in that it's about a man used to living and working in London trying to get the hang of how people live in the countryside. It's packed with entertaining set pieces, such as Howard discussing how to destroy the infestation over a pint at the local pub, and one hilarious sequence involving a Microsoft Word document that turns people into flesh-eating zombies.
Equoid's gradual shift into a proper horror story is so subtle and gradual that you might not even notice it at first. But then you're at the third act, and the Laundry are storming where the "mummy horse" has made its nest with firearms and explosives, and it's extremely effective stuff. From trying to find ways to fight giant, carnivorous horses that weigh as much as a car, to figuring out what to do about the unicorn's mind-slaves, it's frightening and exciting in equal measure, a lot like a game of Call of Cthulhu. And then Howard enters the nest itself. It would be a huge spoiler to describe what happens, but suffice it to say that the final image Equoid leaves you with will haunt you.
It's always fun to see new interpretations of the Cthulhu Mythos, and this is one that manages to keep the same sense of unknowable cosmic horror while putting its own surprisingly light-hearted stamp on it. It's short enough to be comfortably read in a day, and comes highly recommended for Lovecraft fans.