After the experience with 'Será tu tierra,' Soler becomes aware of this cruel reality, until then unknown; Soler makes this documentary on his own initiative and with complete freedom. The film analyzes and quantifies, using extensive data, the social and economic consequences of internal migration during the 1960s, especially in Barcelona and its metropolitan area, focusing on the problems that arise from a lack of housing, with people crammed together in old apartments without hygienic conditions; and the phenomenon of shantytowns.