In the closing months of World War II, a Russian lieutenant named Levka Kosilev is saved by a squad of Americans led by Ben Delaney. Delaney expresses his gratitude to te English-speaking Levka.
In 1950, during the Korean war, Levka - who has grown to become disillusioned with the Soviet regime - is stationed in North Korea near the border with China. He finds that his old friend Delaney is amongst a group of American soldiers taken into China as prisoners, and decides to ensure that the Americans are treated fairly as a way of repaying his debt. Levka ends up losing an argument with a Chinese major named Xhai, who wants the Americans sent into forced labour.
On his way back, Levka is ambushed and taken prisoner by a squad of Americans led by Sergeant Gerry Roberts. Roberts reveals that he and his five men are the only survivors of a platoon that had been attacked by a North Korean unit and, with no maps or navigational equipment, force Levka to act as a guide.
The Americans are determined to complete their platoon's original mission of destroying an anti-aircraft battery, but Levka dismisses this as suicide and tries to convince them to free their imprisoned countrymen. The Americans dismiss this as a trick, and so Levka is forced to go along with their original plan.
The group comes within sight of the battery, but find that it is too well-guarded to attack without more manpower. Levka reminds them of the prisoners, and the Americans, still distrustful, are eventually convinced to make a rescue attempt.
Reaching the Chinese camp, the men create a diversion by blowing up a shed filled with dynamite and manage to infiltrate the prison. While the prisoners are helped to escape, two of the Americans take out a radio hut; two Chinese men are forced at gunpoint to drive Levka and the Americans out of the camp unseen. Outside, Levka and Delaney are reunited. Meanwhile, Major Xhai sees what has happened an sets off with reinforcements to find te culprits.
The Americans resume their attack on the battery, with Levka joining in using a machien gun taken from a fallen Korean. The anti-aircraft guns are successfully destroyed, but soon Xhai manages to track the Americans down.
The Americans outnumbered by Chinese soldiers, Levka hits on a last-ditch idea: he radios his comrades in Korea, pretending to be Xhai and calling for a rocket strike. The strike arrives and kills the Chinese soldiers.
Levka bits farewell to the Americans. Along the way he is shot and injured by Xhai, who had managed to survive the rocket strike, but Levka manages to shoot him back, killing him.
The injured Levka is found by a passing North Korean squad; he tells them that he was strafed by a jet and they drive him to an aid post. His wound does not bother him, as he knows that it will allow him to be flown back to his family in Russia.