In 1863, during the American Civil War, a Southern belle named Carla Forester (Eleanor Parker) visits her friend's wedding at Fort Bravo, a Union prison camp in Arizona, where she helps free Confederate prisoners, including her former beau Captain John Marsh (John Forsythe). With their help, they escape into the desert, only to be pursued by hostile Mescalero Apaches. As the group is hunted down, Carla unexpectedly joins the escapees, giving them an advantage. Roper, the strict disciplinarian Captain (William Holden), must confront his own feelings and motives when he walks out into plain view, allowing the cavalry to rescue him just in time.