The book The Blood of Olympus  by Rick Riordan is about demigods who must save the world from monsters and gods. In the Blood of Olympus nico,Reyna, and coach hedge are escorting the anthena partheons to camp half blood hill but they had to stop in pompeii. Just as they were leaving reyna heard coach hedge talking in a very womanly voice the coach turned around and looked as though he was possesed it was gaea she summonded the ghosts of pompeii to try to kill but the ghost were encased in solid rock reyna's dogs lunged at the ghosts one killed a ghost but the other not so lucky. Nico had summoned some roman ghost worriors which reyna controlled being a roman prateor. but then nico septer broke the ghosts started dissapearing and every thing went wrong.  The Blood of Oympus is a very exciting and interesting book.