This blend of Lovecraftian horror and spies is excellent. Unlike Stross' (also excellent) Laundry Files series, the story is played straight, with little humor. It's dark, but there's a poetry to the prose that draws you down deep into the story in a way that makes it almost impossible to set the book down.

Trying to describe it in any more detail won't do it justice. Suffice it to say I was mesmerized.