Underworld By Meg Cabot

Escape from the realm of the dead is impossible when someone there wants you back.

Seventeen-year-old Pierce Oliviera isn’t dead.

Not this time.

But she is being held against her will in the dim, twilit world between heaven and hell, where the spirits of the deceased wait before embarking upon their final journey.

Her captor, John Hayden, claims it’s for her own safety. Because not all the departed are dear. Some are so unhappy with where they ended up after leaving the Underworld, they’ve come back as Furies, intent on vengeance…on the one who sent them there and on the one whom he loves.

But while Pierce might be safe from the Furies in the Underworld, far worse dangers could be lurking for her there…and they might have more to do with its ruler than with his enemies.

And unless Pierce is careful, this time there’ll be no escape.
 
- Goodreads Summary