Barcelona was the first city systematically bombarded against the civilian population in a war during the Spanish Civil War by German and Italian air armies. Ramon Perera, a 31-year-old engineer, the design of a system that would allow the population to take refuge from air attacks. It involved the construction of air-raid shelters that could be accessed through the staircase of a block of flats or from the street itself. A passive defense design. This series tells different stories within one of these shelters.