Deviant cities are disciplined by Judges dispatched by the Central Government who have control over "seeds" programmed to promote rapid growth. In the event of an affliction affecting the "Children of Babel," Central seeks information from a natural Judge, such as Sion, who has been conferred with power through ongoing research. However, Central is also intrigued by the "Heavenly City," which lends its name to Sion, and their true motivation remains unknown.