In 1954, during the French Indo-China War, the French military outpost at Dien Bien Phu is surrounded by massive Communist Viet Minh forces. A French division of 13,000 men is encircled by four enemy divisions. During the intensive enemy artillery bombardment, the only French landing strip becomes unusable. This means the French garrison at Dien Bien Phu can only be supplied by parachute drops. The French garrison is desperately short of men, ammunition, food, fuel and medicine. To make matters worse, a Chinese officer has infiltrated the base and was sending vital military information to the enemy until he was captured by French army intelligence. The enemy knows the exact number of French troops at Dien Bien Phu, as well as their weapons, morale and supplies. The enemy also knows the rough location of the smaller French fire-bases in the valley. Short of officers, the commander of French forces at Dien Bien Phu, General Christian De Castries, radios Paris for reinforcements and materiel. Paris decides to send reinforcements to Dien Bien Phu. The reinforcements arrive in French-controlled Hanoi by military transport planes. From there they are ferried by helicopter to the French garrison at Dien Bien Phu. Some supplies and paratroopers are also dropped-in by parachute. Among the paratroopers are four replacement officers. They are Captains Guy Bertrand and Jean Callaux and Lieutenants Heinrich Heldman and André Maupin. The stories of their backgrounds and decisions to volunteer for Dien Bien Phu are told in flashback. Once parachuted inside the French garrison at Dien Bien Phu, the main story of these four French officers follows their individual combat performance and their eventual fate within the larger context of the ultimate fate of the whole French garrison.