The distant future. Earthlings help less developed civilizations overcome difficult stages of development. Anton, an employee of the Institute of History, is sent to medieval Arkanar to save scientists who can advance progress. He will have to become Don Rumata of Estor — a wealthy aristocrat, a lover of fights, drinking, and women. The main rule of the progressors is not to interfere directly in the natural course of history, but to save the few enlighteners from destruction on a case‑by‑case basis. However, Anton has a personal interest that he concealed from the Institute: his father went missing somewhere in Arkanar.