After WW II many young people arrive to Zagreb, among them a young worker Sonja Kacar. She is supposed to participate in the construction of the first generator in the Rade Koncar factory. Because there aren't enough experts and materials in Yugoslavia, the factory counts on help from fellow communist countries, Czechoslovakia and Soviet Union. However, after the Inform Bureau's resolution this help is no longer available. Sonja experiences a great intimate disappointment because Stjepan, who she is in love with, supports Stalin