Angels in the world have little to do with heaven - instead, they are incredibly powerful and long-lived creatures who control the world. They also create and control vampires in exchange for a contract of servitude.
Elena Deveraux is a bounty hunter who retrieves vampires when they break their contract. She gets in over her head when the Archangel Raphael hires her personally.
In the future, ruling humans with psychic powers - the Psy - have eschewed all emotion while the were-human Changelings embrace it. Romance between the two is forbidden, but you know what happens when you forbid love ...