What are some really good books that are like these?

Fever Series by Karen Moning- If you have a kindle or a nook, then the first book (darkfever ) is a free for a limited time! Anyway, This series is really really good. It's like a jigsaw puzzle that you have to piece together. It will keep you thinking and wondering :) It's full of suspense, action, drama, and a touch of romance. You will love it!!