If this story had come out ten years earlier, I would never have let my daughter play with those MyLittlePony things. But she grew to love giraffes instead of horses or unicorns, so I suppose that worry would've been for naught anyway. At least until Stross pens something horrific about those ungainly ungulates.
If you're new to the Laundry Files, this series is a bit of James Bond battles Lovecraftian beasties and the occult with a healthy dose of The Office thrown in. But our intrepid hero (Bob Howard) resembles John Oliver more than Daniel Craig. In Equoid, Bob is sent to investigate reports of an equoid infestation (unicorns) at a farm in southern England.
Stross has managed to take the wholesome creature of little girl fantasies (here's why) and, after running it through a Lovecraftian filter, turned it into a horrific monstrosity replete with squishy, icky things and pubescent nightmares (If I had read this at 14...[shudder]). It's so bad that, in all seriousness, some readers will be genuinely disturbed by the imagery. But it all fits. If you understand Lovecraft's universe and the biology of anglerfish well enough, you'll recognize that none of the horror is gratuitous.
Stross also offers a glimpse into what drove the first of several nervous breakdowns that HPL suffered during his teens. He does so by offering snippets of a letter "written" by HPL, which the Laundry has on file. I think Stross did a great job mimicking HPL's style for the letter.
If you've read any of the books in the Laundry Files series, you'll be familiar with the writing style and story structure. It's a great addition to the series, and I highly recommend it to all those who enjoy it.