Sky High

This book is similar in vein to Hugh Howey's Wool, in that it takes place in a dystopian, or post apocalypse world, where a group of teenage orphans are determined to escape the tortures of a mile-high city government—a literal platform city in the sky. They seek the refuge of a utopian society that they believe is rumored to exist. However, all is not well when they reach terra firma. They have escaped a communist dictatorship to land in a world of rogue tribes and hybrid monsters.