This is an adventure film based on a story of the same name by A. Avdeenko. The action takes place at the end of 50s in Zakarpatye. Two diversionists cross the Soviet border near Tissa. One of them is killed at detention and the second appears in a state farm pretending to be a serviceman Ivan Belogray and starts courting Terezia with whom he is acquainted by correspondence. Frontier guard Andrey Smolyarchuk who falls in love with Terezia is the first to suspect Belogray. Thanks to vigilance of law-enforcement bodies the spy is exposed and the prearranged explosion of the railway bridge is prevented.