She starts out trying to prove that she is good and worthy of her mother's love by killing the things that her mother hates, namely vampires. Along the way she meets "Bones" and a whole new world opens up for her. This was not an easy task as she had to resolve her own prejudices about vampires that had been ingrained within her. The reason this is hard is because Bones is a master vampire willing to take her on as a student to teach her ways of killing vampires. His lessons are hard, but in the end she finds a way of accepting who she is and who he is as well. All seems like a hitman's fairytale as the two main characters fall in love. Of course not all is well and the book does not end with a sigh.
Does she keep her new found sense of self? Do Bones and Cat "live" happily-ever after? Exactly what could come between them? Sorry, don't want to spoil the book for you, but let me say, this book is worth a read. It leaves you wanting to read the next in the series.