...Смена начинается в шесть

The events take place in one of the mines of Kryvyi Rih. Peter Chumak, after graduating from the institute, is appointed chief engineer of the mine. From the very first days of work Chumak initiates innovative methods of coal mining. The most fierce opponent of his proposals - engineer Alexei Zheleznyak. The confrontation of young specialists is complicated by the fact that Zheleznyak is the brother-in-law of Pyotr's wife.