Fallen by Karin Slaughter

 Fallen is part of the Will Trent series. In this chapter, his partner Faith's mother is kidnapped after a violent attack in her home. Faith enters the house without realizing the bad guys are still there and ends up shooting 2 of them, which puts a target on her back. The challenge is to figure out who kidnapped Evelyn and why.  Will's boss, Amanda--who has known Evelyn forever--thinks the motive is money. But Will thinks the motive is more personal, and Faith is beginning to think he's right. There was a good twist at the end.

At the same time, Will and doctor Sara Linton are getting closer. But Will's estranged (and very erratic) wife, Angie, isn't about to let him go.