1975 - Cold War between the USSR and the USA, an arms race. Nuclear physicists are working hard. In the Soviet Union, a leak of classified information about the development of the Satan rocket is becoming apparent. It would seem, how can a police major be connected with the intelligence of the special services? However, it was he, Ivan Petrovich, dismissed from the Moscow Criminal Investigation Department, working as an ordinary precinct officer, who provided invaluable assistance to the KGB in the capture of an American spy.