Halfway to the Grave is the first novel in the Night Huntress series by Jeaniene Frost. I purchased this novel at one point because it was featured and recommended by some form of media (which I now don't remember) as being one of the best paranormal romance novels. I'm glad I listened, because Halfway to the Grave lives up to its hype, and I've already added the next book in the Night Huntress series to my reading wish list.
Catherine "Cat" Crawfield is half-human, half-vampire - the result of an unwanted coupling between her mother and the vampire who raped her. These days, the 22-year-old red-haired vixen spends most of her nights hunting and killing vampires to fulfill her mother's wishes of killing off the entire vampire race.