It's a Christmas 1944 for the American POWs in Stalag 17. For the men in Barracks 4 have to take care of a problem that is grave - there looks like a security leak. The Germans appear to be forewarned about leaks and in the latest effort the two men, Johnson and Manfredi, walked into a snare and were killed. For a few in Barracks 4, especially the loud mouthed Duke, the leaker is obvious: J.J. Sefton, a wheelerdealer who does not hesitate to trade with the guards and who has acquired goods and privileges that no additional captive seems to own. Sefton simplifies providing the Germans any advice and makes it clear that he does not have any intention of trying to escape. He plans to ride out the war at but it doesn't expand to spying for the Germans.