A guide, Sergei, and three
geologists—Tanya, Andrei, and Konstantin Sabinin—are brought by plane to the
boreal forest of
central Siberia to search for diamonds. During the plane ride, Konstantin begins writing a letter to his wife detailing his feelings about the expedition. Early on in their search, Sergei expresses jealousy toward Andrei, who is the object of Tanya's affection. Tensions rise between the two while bird hunting for food, resulting in Sergei punching Andrei in the face. After failing to find diamonds while panning in rivers, the group begin a protracted job excavating on a mountainside with pickaxes. When they have reached the point of complete exhaustion, Tanya finally spots diamonds in the earth, leading the group to carry on a rapturous celebration. Andrei uses his radio to inform the base camp in
Petrov about the discovery, and the group prepare to return to civilization, packing their supplies in their canoe. In the middle of the night, they awaken to find themselves in the midst of a
forest fire. Sergei attempts to obtain some of the supplies packed in the canoe but is killed when a burning tree falls on him. Using his radio, Andrei contacts the Petrov base camp, but the receivers are unable to hear them; they merely congratulate the group on their discovery, as well as its significance for the Soviet Union, informing them that they have received a congratulatory
telegram from Moscow. Shortly after, the trio receive a message via radio that search parties have begun looking for them. An aircraft dispatched to search for them flies overhead, but they are unable to get its attention. The group presses on but is forced to carry an injured Andrei on a makeshift gurney. Andrei, feeling himself to be a burden, begs Konstantin and Tanya to abandon him, but they refuse. Upon waking one morning, Konstantin and Tanya find that Andrei has disappeared, devastating Tanya. Konstantin and Tanya press on, encountering another plane overhead, but again are unable to get the pilot's attention. Defeated, the two lie down on a hillside to rest, and awaken covered in snow. As the weather conditions worsen, Tanya eventually succumbs to the elements, leaving Konstantin alone. Still determined, Konstantin uses a makeshift raft to float down the frozen river. En route, he has a vision of himself returning to safety, greeted by his wife Vera and their son. Konstantin eventually loses consciousness, and his raft drifts into a snowbank on the river. Shortly after, searchers in a helicopter spot him lying in the snow, and descend upon the river. They initially presume him dead, but while they listen for his heartbeat with a stethoscope, he slowly opens his eyes. ==Cast==