The main couples from books 1 and 2 (Ric/Megan and Aidan/Elise) appear here. Fianna was punished in the previous book by making her become human and live as one. She works for Greg. Greg has the hots for her and she for him.
Fianna is almost 100 years old who has had one sexual experience. Of course the one time was horrible and the person not nice. As a consequence, she hasn't been interested in sex once. Enter Greg. I think you can guess what happens next. Predictable, but works.
The mystery/underlying events from previous books carry over into this one with some resolution.