Documentary about the building of blast furnaces by the communist youth workers organisation Komsomol, constructed as part of the first five year plan of Stalin's Soviet Union. The film is set Magnitogorsk in the de Ural, where an industrial city of over 200.000 people was built in just a few years, and in the Kubas basin in Siberia. The film is a tribute to the achievements of the volunteers, the Komsomol, but does not show the dark side of history: the thousands of imprisoned Kulach doing hard labour under terrible conditions. Influenced by the Russian filmmaker Vsevolod Pudovkin, Ivens tells the story by following one non-fiction character, a non-actor, who re-enacted the scenes. this form of 'personalised story', which we would call docudrama, reappears after this first attempt in Komsomol in many Ivens films.