Petr, a recently discharged officer, arrives in a tiny mining town in the remote Siberian taiga to hunt for gold. When he finds it, the other prospectors cannot forgive his luck.

A group of scientists is sent to the planet Arkanar to help the local civilization, which is in the Medieval phase of its own history, to find the right path to progress. Their task is a difficult one: they cannot interfere violently and in no case can they kill. The scientist Rumata tries to save the local intellectuals from their punishment and cannot avoid taking a position.