William Holden plays Captain Roper, the warden of a Union-run prison camp. A mysterious woman named Carla Forester (Eleanor Parker) arrives at the camp in order to free the Confederate prisoners, and things get complicated when Carla and the Captain begin to fall for each other. In his efforts to recapture the escaped prisoners, Roper has a run-in with a group of Mescalero Native Americans. His only hope for survival is to team up with the very people he’s imprisoned as they combat a mutual threat.