British POWs in Burma are employed by the Japanese to build a bridge; meanwhile, British agents seek to destroy it. After surrendering his unit to the Japanese. Colonel Nicholson demands his men behave by the book, and refuses to cooperate with the equally dutiful Japanese commander. When the Japapese insist that the POWs build a bridge, they decide to build the best one possible, thereby restoring morale. But after one of the men escapes to Australia and lets the British commander there know of the operation, he is sent back to the jungle to destroy the tactically-crucial bridge that his comrades are desperately trying to complete.