Sixteen-year-old Fish—white-haired throwback and embarrassment to his village—is shoved across the border into the Arid Zone and told to vanish.

Survival means finding the outlaw brothers who want nothing to do with him, dodging rebel ambushes and Southern raiders, and learning the brutal rules of Megalopolis: the five-walled silver city that trades weather-control for the Zoners' food. Armed with little more than a flute, a hunting knife, and an unshakeable belief that the world's cruel divisions can change, Fish stumbles into a conspiracy for stolen Knowledge Chips—devices the Megas use instead of learning. If he can't outwit city guards, rival scavenger clusters, and the sinister High Mega who covets his strange green eyes, he'll lose far more than his freedom.

Pushed over the wall, but never willing to stay in a box, Fish will either rewrite the rules—or die an Outcast.