While trying to cross the State border of the USSR, a resident of one of the Western intelligence services was detained and committed suicide, who wanted to take out from Soviet territory a film shot at one of the defense facilities. From abroad they send for a duplicate of the film the granddaughter of one of the closest associates of the Basmachev leader Ibrahimbek, who inherited from her grandfather a fierce hatred for the Soviet country, and the son of a man who sold his homeland during the war years ...