Heroes Of Olympus: Blood Of Olympus (book 5) by Rick Riordan

Though the Greek and Roman crew members of the Argo II have made progress in their many quests they still seem no closer to defeating the earth mother Gaea Her giants have risen all of them and theyre stronger than ever The gods still suffering from multiple personality disorder are useless How can a handful of young demigods hope to persevere against Gaeas army of powerful giants As dangerous as it is to head to Athens they have no other option They have sacrificed too much already And if Gaea wakes it is game over