The Rhesus Chart (Charles Stross)

Stross writes intelligent, funny, surprising science fiction, and his Laundry series is all of the above. This recent example lives up to the others. Bob Howard works for a top-secret British intelligence service, defending Queen, country, and universe against many-tentacled horrors from beyond the veil, through diligent application of the principles of government bureaucracies everywhere: paperwork, committee meetings, organizational hierarchies, and very bad coffee. The current crisis begins with a group of math whizzes working on algorithms that will allow their investment bank to anticipate market trends more effectively than their competition, and unwittingly trigger an outbreak of V-syndrome (you know, the one where you burst into flame in direct sunlight, develop a craving for human blood, are stronger than normal humans, and can exercise control over other people's minds). What is behind this new nest? Is there an enemy planted within the Laundry itself? And what does Bob's malevolent, unstable ex have to do with things? It's a fun ride from start to finish.