If you haven't read House of Hades yet this will be a little confusing and will contain spoilers. Percy and Annabeth had gotten out of Tartarus and are now continuing their quest to Mt.Olympus. The original one in Greece. But everything isn't back to normal yet. Percy and Annabeth are still recovering from their journey in Tartarus causing them to grow distant which leads to even more ways for Gaea to play with. Leo is still struggling on finding Calypso and is sure that he will never find him. Nico is also confused about his relationship with Percy and what he will do. Nico Reyna and Coach Hedge continue their journey back to Camp Half blood. Together these two groups of half bloods will bring peace to the ongoing feud between the Roman and Greek demigods and decide whether they will continue living in their home planet or if it will be conquered by evil, ending their lives forever. Note that I don't own the Heroes of Olympus series. This goes to Rick Riordan. heck if I was writing the series it wouldn't be nearly as good As Uncle Rick's though I would've probably put a lot less teasing and torture :). Vote and Follow and recommend it to other Percy Jackson fans:)