The cover of Ghost Camp shows a line of ghostly campers, invisible save clothes, while a human girl at the back stares in horror. Seems to be a straight case of Covers Always Lie, since the protagonists are boys and nothing like this happens in the book. Then you realize that Harry and Alex probably aren't the only campers who have been coming here. And the ghosts' goal is to find new bodies, meaning at least one lucky camper might be out there living this poor girl's life.
