Stuck in Tartarus with one chance at getting Annabeth out alive, Percy chooses exile. But this new world he's forced to isn't one like his own. Humanity is relegated to corners of the globe, it's just unfortunate that his corner happens to be run by murderers and thieves. But he has no choice but to join them if he wants to save this world in time. Some things never change.

The gods are weakened after the giant war to the point of fading, and approach their children with a demand, a last resort; invade Manhattan to secure Olympus and gain them worship, to keep them from fading. Percy reluctantly leads the Half-Blood expedition west, but the gods have never known when to leave good enough alone, and they weren't about to start.