A band of determined Russian soldiers fight to hold a strategic building in their devastated city against a ruthless German army, and in the process become deeply connected to a Russian woman who has been living there.

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.