The Rhesus Chart by Charles Stross is the most recent full-length novel in the Laundry Files, an on-going series that combines espionage, bureaucracy, and cosmic horror equally, and it's sometimes difficult to separate the three. It is also probably the best book in the series thus far.
Without giving anything away, The Laundry comes into contact with vampires (the non-sparkly variety) and it all goes horribly wrong and downhill from there. I'm marking this as the best in the series because of all the books in it thus far, The Rhesus Chart has the most straight-ahead plot without limiting complex subplots, the most character development on multiple levels, and a wrap-up that left me just saying "daaaaaaaamn" over and over again. It's an incredibly quick 370 page read, which is unfortunately because you really don't want it over and done with as quickly as it is. Very well done, 5 stars.