Alice Grey is a Guardian with her soul on the line: either she must kill Michael, head of the Guardians, and present his heart to a demon, or else she'll be damned for eternity. Finding a way out of the bargain involves a lot of archaeological investigation, more history of the Guardians and Heaven and Hell, and the help of novice Guardian Jake Hawkins.
The plot does not make much sense to me, nor do the eventual revelations about Guardian history, which I still fail to understand. On the other hand, I am perfectly willing to sacrifice plot comprehension and logical worldbuilding for angels and demons and heaven and hell and lots of crack (see also:
Yuki Kaori). Brook is not quite as cracktastic as Yuki Kaori, but given the three things I've read by her so far (this book,
Demon Angel, and a to-be-blogged short story, I think I will keep reading and hoping that she improves in her characterization.
The notion of Alice as a character is awesome. She's known as the Black Widow to the Guardian novices, most of whom are scared silly of her; she keeps pet spiders (normally freaky but very cool when there are no visuals); she freaks Jake out by projecting the illusion of a spider crawling out of her lips the first time he kisses her (again, normally freaky but very cool when there are no visuals); and she has tons of angst thanks to her backstory and to her bargain with a demon. The execution of Alice as a character is not quite as good. The backstory might have been effective had it been more interwoven with modern-day Alice; as such, I didn't fully believe in what she had suffered before becoming a Guardian. Also, much like in Demon Angel, once we get to the sex, all the tension in the story and between Alice and Jake vanishes. Sometimes she felt more like a composite of traits rather than a human being.
Still, I enjoyed the book a lot, and I'm particularly happy that the sex is not perfect the first time around and that there's characterization during the sex scenes. And I find Jake's puppy-dog-ness very cute, although some of the "Hot damn" dialogue and his own backstory didn't work for me. Overall, Brook seems to be very uneven as an author and doesn't always succeed in what she attempts, but what she attempts is so interesting (particularly for the romance genre) that I'm curious to see what she'll continue to write. Also, it's so nice getting some paranormal romance writers who have grown up on SF/F and comic books as much as they've grown up on romances; it's such a change from many of the older paranormals I used to read, where the worldbuilding was a joke. Brook's worldbuilding is not necessarily coherent or logical, but there sure is a lot of it, and it's very fun.