Night Huntress Book 2. One Foot in the Grave

You can run from the grave, but you can't hide... Half-vampire Cat Crawfield is now Special Agent Cat Crawfield, working for the government to rid the world of the rogue undead. She's still using everything Bones, her sexy and dangerous ex, taught her, but when Cat is targeted for assassination, the only man who can help her is the vampire she left behind. Being around him awakens all her emotions, from the adrenaline kick of slaying vamps side by side to the reckless passion that consumed them. But a price on her head wanted: dead or half-alive means her survival depends on teaming up with Bones. And no matter how hard she tries to keep things professional between them, she'll find that desire lasts forever... and that Bones won't let her get away again.