In an isolated society, teenage Erith has been chosen for Polishing, a ritualistic surgery that erases one's irises so the individual may see the Volucris—strange and enigmatic creatures that live in an alternate realm only visible to the Polished. She discovers a new, haunting reality after her procedure that warps light into darkness and reveals hidden secrets about the world. As she progresses, she and her companion, Calyx, discover frightening truths about the Polished and realize they are in danger of losing themselves to the changes Polishing inflicts on the mind.