In 1948, when Hungarian industry counts on almost every liter of fuel, the production of Makert, an American oil company in Hungary, is declining by the day. The firm's American owners claim that the oil field is depleted. However, the new government controller, Nerges, discovers that this is sophisticated sabotage by which representatives of American industrial circles want to disrupt socialist construction in the country. With the help of Hungarian state security officers, Nergesz uncovers and neutralizes the saboteurs at the mine and hastens the Hungarian people's decision to nationalize Makert.