Hazel, Nico, Piper, Leo, Frank y Jason han descubierto que la parte exterior se halla en Grecia, en el templo de Hades, dios del inframundo, aunque tienen un largo viaje hasta allí e ignoran a qué deberán enfrentarse cuando lleguen. Mientas, Percy y Annabeth se encuentran en algún lugar al otro lado, luchando por su supervivencia, por encontrar las puertas... y por salir antes de que sea demasiado tarde. At the conclusion of , Annabeth and Percy tumble into a pit leading straight to the Underworld. The other five demigods have to put aside their grief and follow Percy's instructions to find the mortal side of the Doors of Death. If they can fight their way through Gaea's forces, and Percy and Annabeth can survive the House of Hades, then the Seven will be able to seal the Doors from both sides and prevent the giants from raising Gaea. But, Leo wonders, if the Doors are sealed, how will Percy and Annabeth be able to escape? They have no choice. If the demigods don't succeed, Gaea's armies will never die. They have no time. In about a month, the Romans will march on Camp Half-Blood. The stakes are higher than ever in this adventure that dives into the depths of Tartarus. This paperback edition will include a never-before-seen short story, "The Crown of Ptolemy," in which Percy and Annabeth fight alongside Carter and Sadie Kane, and more bonus content!