The fortress-city of Pingwot, besieged for six centuries, has attracted the Universal Church's attention by flaunting pre-apocalyptic technology. Father Bertolo is sent to discover the source of their sudden enlightenment. He fears the citizens of Pingwot have stumbled on an ancient cache of information, but the truth is much worse: he might have to call down a Holy Crusade to destroy the city and save mankind from destroying itself yet again.