During WWII a group of Americans were incarcerated in a German POW camp called Stalag 17. After an escape-attempt-gone-wrong that resulted in the deaths two men, prisoners in their barracks start suspecting there is a German stoolie in their midst. Sefton (William Holden) is the chief suspect. He's a wheeler-dealer who always seems to get extra perks the other men don't get. After Sefton bribes guards in order to spend a night in a women's barracks, his barrack-mates are convinced he's the snitch and beat him severely. In order clear himself, Sefton decides to find the real culprit. Amidst this two new prisoners arrive including Lt. James Dunbar (Don Taylor). Dunbar’s companion boasts that Dunbar was responsible for blowing up a crucial German bridge. Of course, this information gets back to the Germans who immediately seize Dunbar for questioning. When the men hear that Dunbar's to be taken to Berlin, they hatch a daring plan. While causing a major distraction, they hide Dunbar. The Nazis are furious when they can't find him. Sefton, in the meantime, has learned who the stoolie is. Using the informant as a distraction for the Germans, Sefton and Dunbar make their escape.