The book introduces the reader to Justinian the Great (527–565), the most famous and mysterious emperor of Byzantium. An experienced politician and a brilliant strategist, he formed a stable government, passed new laws and managed to restore the Roman Empire. The author tries to prove that Justinian adopted the ideas of the Iranian Mazdakite sect, which some scholars call “communist”. It was the Mazdakites who had a huge influence on the fate of the emperor. The book contains many parallels with modern times, and its main idea - social renewal and restoration of imperial borders - is relevant for modern Russian society.