The House of Hades is the fourth book in the bestselling Heroes of Olympus series， set in the action-packed world of Percy Jackson。 The stakes have never been higher。 If Percy Jackson and Annabeth fail in their quest， there'll be hell on Earth。 Literally。 Wandering the deadly realm of Tartarus， every step leads them further into danger。 And， if by some miracle they do make it to the Doors of Death， there's a legion of bloodthirsty monsters waiting for them。 Meanwhile， Hazel and the crew of the Argo II have a choice: to stop a war or save their friends。 Whichever road they take one thing is certain - in the Underworld， evil is inescapable。 The Lost Hero: When Jason， Piper and Leo crash land at Camp Half-Blood， they have no idea what to expect。 Apparently this is the only safe place for children of the Greek Gods - despite the monsters roaming the woods and demigods practising archery with flaming arrows and explosives。 But rumours of a terrible curse - and a missing hero - are flying around camp。 It seems Jason， Piper and Leo are the chosen ones to embark on a terrifying new quest， which they must complete by the winter solstice。 In just four days time。 Can the trio succeed on this deadly mission - and what must they sacrifice in order to survive？ The Son of Neptune Percy Jackson， son of Poseidon， God of the Sea， has woken from a very deep sleep and come face to face with two snake-haired ladies who refuse to die。 The Mark of Athena Can Percy Jackson and the Half-blood Heroes succeed on their quest to find The Doors of Death or will the Greek Gods of chaos win their battle to stop them？ Percy and his fellow demi-gods face the most important quest of all - the Prophecy of Seven。 The Demigod Diaries Percy Jackson and Annabeth must rescue stolen goods from a fire-breathing giant who doesn't take kindly to intruders。