"Secret! - The Iron Problem of Socialism" is a comprehensive non-fiction book that addresses the challenges and experiences of the BAK Kriwoi Rog. Written by Rolf Junghanns, the work sheds light on the complex interconnections and the diverse human destinies associated with the construction project. Despite the enormous efforts and the involvement of thousands from various countries who worked on this endeavor for years, the tangible result remains elusive. The book not only provides a detailed depiction of the combine and its dimensions but also offers insights into the tumultuous period of Perestroika and the political upheavals in Eastern Europe. Junghanns recounts the hopes and disappointments of the people involved in this project, presenting a striking picture of the collaboration and cultural encounters between the construction workers and the people of the Soviet Union, particularly Ukraine.