"The Informer!"
The Howling Commandos get themselves captured by the Nazis in order to rescue Jim Morita from a Nazi prison camp. Once in the camp, the Howlers discover that one of their fellow prisoners is an informer who has been feeding the Nazis information about escape attempts. Nick Fury and his men will have to outfox and unmask the traitor if they want to complete their mission.
Reprinted from Sgt. Fury and His Howling Commandos #57.