During the Korean War Lt. Sam Pryor volunteers his platoon to escort Greek troops to perform a reconnaissance mission behind Communist lines. Due to his Greek heritage Pryor is initially proud to accompany the Greek contingent but his feelings change to scorn and mistrust when what he believes is cowardice shown by the Greek soldiers and their leaders results in the near annihiliation of his own platoon. An uneasy alliance is maintained between the US and Greek troops as the enemy's true objective is learned.

In the United Nations campaign during the Korean War, Lt. Sam Prior leads his company of combat engineers in an operation to blow up a bridge that the enemy might want to use. Back at the base, the company commanders discuss a big offensive push planned to begin in seventy-two hours but, due to a number of lost patrols, they suspect that the enemy is hiding something on the other side of the river. The division is sending a brigade of Greek infantrymen trained in guerrilla warfare to scout behind enemy lines, and when the bigoted Lt. Jorgenson expresses dismay at having to work with the Greeks, Sam volunteers his platoon to ferry them across the river. Maj. Sauer warns Sam that many men share Jorgenson's prejudice, but Sam assures him that his soldiers know that his name used to be Priovolos and that his father was Greek. At the Greek camp, Sam introduces himself to Capt. Ton Charos, Lt. Nikias and Corp. Marakis, the company's translator. To assuage his men's misgivings about the Greeks's seemingly carefree attitude, Sam tells them that they have a tradition of being tough warriors. After confirming their orders, that Sam will be in charge while ferrying the Greeks, after which Charos will assume command, the men assemble. Several of the platoon's rafts have been damaged, however, so Sam orders the men to leave the machine guns and mortars behind and take only the weapons they can carry. After landing on the other side of the river, the Greeks set off on their mission, and the Americans are attacked by the enemy, but drive them away. Sam sends Marakis and two men to scout the woods, and they see that about a dozen Greek soldiers have been captured, apparently without a fight. When the Americans learn what has happened, they make disparaging comments about the Greeks and suggest that they retreat because they have no heavy equipment. Sam is determined to support their allies, however, and orders the majority of his platoon to retrieve the weapons while he and Marakis wait with Sgt. Chuck Anderson, Pvt. Stone and demolitions expert Corp. Bowman. As the sun begins to rise, Sam and his men hear gunfire and rush to the river, where they find that the rest of the platoon has been killed. As they survey the damage, a group of twenty-three Greeks, led by Nikias, return, and Nikias reports that they were cut off from the brigade and had to engage in fierce hand-to-hand combat to fend off the enemy. Seeing that their bayonets are clean, Sam angrily accuses them of not fighting as hard as his own men would have, and feels ashamed of his high regard for the Greeks. When they spot an enemy tank, Sam derisively orders Nikias to "lay low," then has Bowman plant dynamite to blow it up. After the charge stops the tank, Sam recklessly climbs to the top and tosses in a grenade, much to the chagrin of Nikias, who considers Sam to be foolhardy. Believing that his trust of the Greeks is responsible for the deaths of his men, Sam determines to move inland to complete their mission, and because Sam possesses the majority of their remaining ammunition, Nikias has little choice but to follow. As they march, they find an enemy camp filled with captured American ammunition and equipment. Determined to recover the ammunition, Sam orders an attack, and although Nikias disagrees with his decision, the Greeks fight bravely, and after the successful battle, Chuck notes that they clean their bayonets immediately. Inside the camp's hut, Nikias berates Sam for taking risks and trying to prove himself in order to contain his guilt. Because the Greeks outnumber the Americans, Nikias assumes command of the company, and when Sam learns about the bayonets from Chuck, he grudingly accepts Nikias' leadership. A wounded New Zealand soldier found at the camp then tells the men that he learned about a massive concentration of enemy tanks and ground troops concealed three miles away. Realizing that headquarters must be informed, Nikias sends two men ahead and orders that an old bulldozer be used to pull a transport to carry the wounded. A short time later, the two messengers are found dead, and Nikias worries about reaching headquarters in time to warn them of the enemy's plans. Just then, a tank is spotted approaching, but Sam and Bowman disable it by setting it aflame with "cugas," or "crazy gas." When an enemy jeep finds the tank, however, Nikias realizes that they cannot reach the river in time with the slow bulldozer, and sends Sam and his men ahead while the Greeks move to a nearby ridge to hold off the enemy. At the river, the Americans discover that the enemy has been secretly building an underwater bridge so that their tanks can attack Allied headquarters. Hoping that one of them will make it alive, the four men decide to swim across the river but are stopped by the arrival of three Greek soldiers. The Greeks inform Sam that Charos had deliberately allowed some of his men to be captured in order to distract enemy patrols and thereby sneak through the majority of his brigade. To protect his men, Sam decides to wait for Charos. After Charos arrives, they are able to contact headquarters, and the company commanders decide to call out air support and use the enemy's bridge themselves. Charos and Sam then lead their men back to the ridge, where they join Nikias in fighting, and soon American planes are bombing the enemy as Allied tanks begin their assault. Helicopters arrive to rescue the Greeks, and Sam, who has apologized to Nikias for his behavior, sits beside his new friend on the last flight out.