I really enjoyed this book. Appalachia has become a religious city-state with limited access to "Outside". Caitlyn is different, and different isn't tolerated in Appalachia. She and her father are trying to escape. In addition to the exciting escape story, Brouwer uses his story to comment on what can happen to a society that loses all its dissidents, either by tossing them out or by them leaving voluntarily. Both Appalachia and Outside are impacted by this loss, in surprisingly similar ways.
A sequel is planned, but this can be read as a stand-alone. I'll be looking for the sequel though. I want to learn more about Caitlyn, Appalachia, and Outside.