This was a real winner. I want more of these characters, now. I've been waiting for this one to come out since I read a pre-publication excerpt, and I was not disappointed when I got my hands on the whole thing.
It is part 1 of a series, and while it does present a satisfying wrap-up of the immediate problem, don't expect all the loose ends to be resolved at the end. There are very clearly hooks for subsequent stories, including an unidentified security leak in the government agency which employs one of the main characters.
Both main characters have very distinct internal voices which provide a sort of running monologue, keeping the reader involved in what they're thinking without being heavy-handed about telling you. I particularly enjoyed the scene where Starkweather tries to perform an exorcism of Gray, thinking he's a demon. Grey throws him completely off his stride with unintentionally snarky replies, and his growing realization that he's in way over his head is beautifully handled.
(reviewed 21 days after purchase)