In a world where plants have been unseen by the masses for over three generations and a beautiful city hosts most of humanity, Ava is simply one of a million children curious about the world but chained within an elaborate, pristine cage that can provide them with safe and happy lives in exchange for their freedom. However, one day, when that curiosity gets the better of her, Ava slips through the cage walls into the decrepit, forgotten Old Capitol and finds herself involved in an underground world she never knew existed. With her as a catalyst, things begin to spiral out of control and the pristine world they had all come to know may never be the same.