In early 1943, British POWs arrive at a Japanese prison camp in Burma, led by Colonel Nicholson. One of the other prisoners he meets is Commander Shears of the U.S. Navy, who describes the horrific conditions. Nicholson forbids any escape attempts because they were ordered by headquarters to surrender, and escapes could be seen as defiance of orders. Dense jungle surrounding the camp renders escape virtually impossible. Colonel Saito, the camp commandant, informs the new prisoners they will all work, even officers, on the construction of a railway bridge over the River Kwai that will connect Bangkok and Rangoon. Nicholson objects, informing Saito the Geneva Conventions exempts officers from manual labour. After the enlisted men are marched to the bridge site, Saito threatens to have the officers shot, until Major Clipton, the British medical officer, warns Saito there are too many witnesses for him to get away with murder. Saito leaves the officers standing all day in the intense heat. That evening, the officers are placed in a punishment hut, while Nicholson is locked in an iron box after getting beaten as punishment. Shears escapes and is wounded. He wanders into a Siamese village, is nursed back to health, and eventually arrives in the British colony of Ceylon.