The Fuller Memorandum — Charles Stross

Computational demonologist Bob Howard is taking a much-needed break from the field to catch up on his filing in the Laundry archives when a top secret dossier known as the Fuller Memorandum vanishes -- along with his boss, who the agency's executives believe stole the file.

Determined to discover exactly what the memorandum contained (and perhaps clear his boss), Bob runs afoul of Russian agents, ancient demons, and the apostles of a hideous faith who have plans to raise a very unpleasant undead entity known as the Eater of Souls.

Now Bob must use all of his skills to learn the secret of the Fuller Memorandum in order to save the world -- and avoid becoming an item on the Eater of Souls's dinner menu...