Sins of the Demon (Kara Gillian Series #4)

The homicide beat in Louisiana isn't just terrifying, it's demonic. Detective Kara Gilligan of the supernatural task force has the ability to summon demons to her aid, but she herself is pledged to serve a demonic lord. And now, people who've hurt Kara in the past are dropping dead for no apparent reason. To clear her name and save both the demon and human worlds, she's in a race against the clock and in a battle for her life that just may take her to hell and back.