After the third world war in the 21st century, Europe has half disappeared under nuclear bombs. The few livable areas are contaminated by radiation from nuclear power plants that have not been made safe. There are two civilizations competing for the territory: the first has taken control of the underground cities sheltered from radiation and professes a religion that sees the third world war as the apocalypse. The second civilization is forced to live in the open air and still professes Christianity. Two brothers, separated during a battle, find themselves against each other as the inhabitants above try to fit into the civilization of the cities below, attracting attention by sabotaging the air ducts.In this context, each inhabitant is marked with a necklace that determines their rights and privileges, to prevent the two civilizations from confusing each other.