Major of the border service Konstantin Kudin serves at the outpost where his father died. A devoted, perceptive, and honest commander, he regularly refuses promotions, which displeases his wife. During a border patrol, Kudin discovers a stone containing spy equipment and thwarts the plans of several groups of criminals: the local businessman Tyurin, who is engaged in drug smuggling; his patron among the border guards; and a group of terrorists planning a terrorist attack in Minsk. In fulfilling his duty, Kudin not only risks his own life but also puts his family members at risk.