The action takes place from April to December 1986. The Ukrainian department of the KGB of the USSR becomes aware of the interest shown by foreign intelligence services in the Chernobyl nuclear power plant. To establish the whereabouts of an experienced CIA officer, Albert Lenz, who is suspected of espionage, on the territory of Pripyat, Lieutenant Colonel of military counterintelligence Andrey Nikolaev arrives in the city.
