Fleeing unending violence and Earth's now-radioactive surface, humans have regrouped to a mysterious platform known as CIEL. The surviving humans have become sexless, pale creatures floating in isolation. Out of the ranks of the endless wars rises a cult leader who turns CIEL into a quasi-corporate police state. A group of rebels unite, galvanized by the heroic song of the child-warrior Joan. When she is killed, the consequences are astonishing.