Afghanistan. 1986. A column of soviet military armour heads from the frontier for Kabul, along a mountain road. It is shielded from air by military helicopters. The way of a column lies through the only bridge in the neighbourhood. Afghan militants are well informed about it, and, led by an American instructor, they prepare a trap. At the moment a Soviet geological expedition, located in mountains, is exposed to a night attack of dushmans (transl. from Afghanian enemy). The Afghan column disperses and geologists decide to go to Kabul. On their way they get information about an approaching soviet column, which would make their trip to Kabul much safer. But they dont know that they are already a part of the operation on the bridge.