Blood Rites by Jim Butcher
It's getting a little difficult to talk about these books too much without giving away spoilers for the rest of the series. In this one, Harry is getting sick and tired of various vampires trying to kill him so he decides to take the offensive and plans an assault on Mavra, the supervillain of the Black Court. Additionally, he is working a specific case that he found through White Court vampire Thomas that keeps showing up. A porn director has noticed that women are dying around him in freak accidents, and hires Harry to protect them and determine who is using such a powerful curse to come after him.
Butcher finally introduces a few more characters from the White Court in this novel since before this, the focus has really been on the Red and Black Courts. He also reveals quite a bit more about Harry's family - it was about time to give us a bit of a bone. Also, Harry gets a puppy.
Butcher definitely has been doing a good job of keeping this series fresh, and adding backstory as he goes. Six books in and the series isn't getting repetitive or boring, so I can appreciate that. As I said, I am not going to go too much into these since it ruins things in earlier novels if I do.