The Fuller Memorandum (Charles Stross)

I'm reading the Laundry Files series out of order, which is a little confusing, but I love them anyway. The mixture of humor, pop culture, computers, science geekery, Lovecraftian horror, James Bond, and soul-deadening bureaucracy really works for me. In this one, we learn a little about Angleton, Bob Howard's very scary boss, and find out why he's even scarier than we thought. Along the way Bob's wife Mo proves her badassery with the demon-killing violin and Bob has to face an army of cultists bent on sacrificing him to the ultimate dark lord, armed with nothing but his knowledge of computational demonology. Great stuff.