For those unfamiliar with the works of H.P. Lovecraft, I would provide a word of warning. In the mouth of madness lie monsters, and likely bad teeth and a few cavities. At least that is what one would assume when reading the imaginative works of Charles Stross, a Scottish science fiction writer whose short stories and novels have garnered numerous award nominations.
Like the famous HBO movies Cast a Deadly Spell and Witch Hunt Charles Stross imagines a world wherein the gibbering terrors from beyond the imaginings of men, generally referred to as Old Ones, and the arcane principles that summon them, are real. Whereas the earlier films are set in the 1940's, Stross uses the computer age as the backdrop for his horror/thrillers.
The Atrocity Archive set the stage for us when it introduced the concept of the Laundry, a super-secret British Intelligence unit dealing with the mathematic insanity of the Turing-Lovecraft Theorum of universally applied mathematics (i.e. at the end of the long chain of complex equations something eats your brain). The main character, Bob Howard, is a tech geek whose sole purpose is to exorcise the summoned creatures from the Laundry's internal network servers (i.e. 'this LAN is clean'). Although he wants a field commission to help keep the world safe from the many angled ones, Bob is really an IT guy at heart and would be just as happy de-gaussing the wiring at the Laundry as getting into shootouts with the Black Chamber and their minions.
The Jennifer Morgue is even better. Imagine this if you will: James Bond/Cthulu/Hackers crossover. That's right. Go buy it now!!!! Even better than the first book, The Jennifer Morgue explores the concept of archetype-casting and forcing people into well known molds. The unfortunate side-effect is the brain-eating monsters from beyond that wait to devour the souls of the few who are actively participating in the endeavor. Small price to pay, really. Seriously, though, Charles Stross' irrepressible writing style and brilliant story combine to craft a truly brilliant piece of workmanship.