I love this series. This is the fourth book in the series, so if you haven't read the first three, please do so.
Kara Gillian is a demon summoner who is also police detective in Louisiana. This specific installment had less to do with procedural stuff, although there are people dying who are related to events in Kara's past, and more to do with demons and summoning. That being said, there are still plenty of loose threads, and the cliffhanger from book 3 wasn't resolved to my satisfaction (yet) and guess what there is a new cliffhanger. But I couldn't put it down, and cannot wait for the next installment!