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.

In this TV-series the events of the beginning of the 20th century in Russia are highlighted. Revolutioners, terrorists, spies - and investigator Putilovskii and his team fight them as best they can.

Military doctor General Klenski is arrested in Stalin's Russia in 1953 during an anti-Semitic political campaign accused of being a participant in so-called "doctors' plot".

Based on the story of the same name by Ivan Kataev.