Hard to be a god

The distant future. Earthlings help less advanced civilizations overcome the difficult stages of evolution. Anton, an employee of the Institute of History, travels to medieval Arkanar to rescue scientists capable of advancing evolution. He is to become Don Rumata Estorsky—a wealthy aristocrat and lover of fights, drink, and women. The main rule of the Progressors is not to directly interfere with the natural course of history, selectively saving a few enlightened beings from destruction. But Anton has a personal interest that he has concealed from the Institute: somewhere in Arkanar, his father has disappeared without a trace.