Beasts of Olympus is a series of 144-page illustrated chapter books set in a magical Ancient Greece where strange things still walk the Earth. In this second book, young Demon is summoned by the great god Hades to the Underworld.His most-hated hero, Heracles, has just returned Cerberus the three-headed dog Guardian of the Underworld to his god master, but something is wrong with the beast . . . and only Demon can help."