The House of Hades Heroes of Olympus, The, Book Four

Follow the seven demigods as they journey through the Underworld to fight the forces of Gaea and prevent the giants from raising her. With Percy and Annabeth trapped in the House of Hades, the stakes are higher than ever. If they can't seal the Doors of Death from both sides, Gaea's armies will never die. This thrilling adventure takes you into the depths of Tartarus, with a bonus short story included in this edition. Will they succeed before the Romans march on Camp Half-Blood?