Ver Cuevana. Semyon Primak, in the direction of the regional committee, arrives in one of the small towns of Donbas and immediately enters into battle with the chief of the mine, Chub, who, in a situation of continuous assault, plays into the hands of the Trotskyites and bandits operating in the mine. Having received moral support from the new secretary, the best 'udarnik', shockworker Matvey Bobylev implements a new method of coal mining and, contrary to the intentions of the enemy group, finds a wide response among the miners of Donbas.