A sheltered young pony raised in an underground refuge ventures out into a devastated, irradiated world to help a friend and becomes entangled in the violent politics, strange mutations, and harsh survivalist culture of the wasteland; along the way she gathers unlikely allies, faces brutal moral choices, uncovers painful truths about the past, and struggles to hold onto compassion and hope while confronting the cost of power and the possibility of rebuilding a broken world.