Storm in a Teacup is the start of a three book series but definitely works as a standalone, too. You'll probably want more, after listening to it, though.
The setting is an alternate universe were demons are common place and kept in check by a policeforce born and bread to fight them. Think of it as Buffy-The-Vampire-Slayer Special forces. Less teenager issues though.
The main character, Ayala, a badass who has to balance a day job and not always understanding job is a great mix of snark, violence and well rounded actual human behaviour and issues (influenced by her situation of course). The other characters do not feel like cardboard cutouts that only exist as props to support the main character.
The story-telling is tight, gritty, at times hilarious (seriously, the similes in this made me laugh out loud several times) and sexy. Amber Benson does a GREAT job of bringing all the characters to life, instead of "just" reading it.
The antagonist(s) arent's just the run-of-the-mill boring uberdemons from a textbook portal just so there's something to slaugher, there's actual motivations behind the whole thing, and it's not as simple and straight-forward as it seems at times.
Suffices to say I loved it and am looking forward to more.