The events take place in 1986 in the Soviet Union. The Ukrainian branch of the Soviet intelligence agency learns that their foreign colleagues are actively interested in the Chernobyl nuclear power plant. Rumors quickly spread that an American CIA agent named Albert Lenza has been sent to Pripyat. The task of the authorized representatives of the KGB is to locate and expose the agent. For this purpose, a lieutenant colonel and an experienced Soviet spy, Andrey Nikolaev, are sent to Chernobyl.