Piper McLean and Perseus Jackson were betrayed by those closest to them. Then murdered by those same people. But they didn't die. Chaos chose them. To be his avengers, the Protectors of the Betrayed. Now they have trained. They thought they would never have to go back. That they would never have to rest their gazes on their faces again. They were wrong, a new enemy is arising, and is the most dangerous the world has ever seen.