The setting is a German Stalag (POW camp). There are Allied prisoners there, both Russian and American. The film is mostly set on the American side of the camp. The German guards are remarkably nice to the American prisoners, which is very unrealistic. Life in the camp is good for the most part and all the Americans look very well-fed (also unrealistic).
Then two American fighter pilots, both black, are brought into the camp and the racism part begins. No one wants them in their barracks, which is realistic. One of them is set up by the other prisoners and is summarily executed. The other is then accused of murdering another prisoner. The prisoners are then allowed to hold an American Court-martial! LUDICROUS! No German commander would allow something like this to happen in their camp. He even helps the defending attorney (who had been a Yale law student pre-war). Turns out, the Kommandant is a Yale graduate - how convenient!
In short, the entire plot is so full of holes that you could drain spaghetti with it. However, there are a couple of bright spots...look for good performances from Colin Farrell as Hart and Marcel Iures as the Kommandant. I wouldn't recommend this film unless you are bored.