Government authorities tell their citizens that decades ago, a virus killed most of the humans living on Earth. To prevent the eradication of the human species, the government has imposed the permanent isolation of adults, two by two, in cement chambers located in the heart of underground facilities. Locked up together for years, an ambitious young man and a good-natured old man have the daily task of turning valves fixed to the wall to distribute drinking water to a thirsty population. A chance reunion with a childhood friend could allow the young man to realize his dream of escaping their cell... and lead them to finally see the light of day.