My book Abandon by Meg Cabot is about a girl who died when she was 15 and came back to life. But while she was dead she met a person in the underworld (where the dead go before going to their final destination, either heaven or hell) and then remembers an accounted with him previously when she was seven. They both fall for each other but think the other hates them. The guy from the underworld, John, gives pierce a magical necklace which is meant to worn her when evil is around. When they finally see that they love each other he takes her back to his underworld.
I give this book a rating of 5 out of 5