At the Union stockade at Fort Bravo, Arizona Territory, Confederate prisoners watch, enraged, as bedraggled escapee Bob Bailey is brought back to the camp on foot by the steely Capt. Roper. Although the camp commander, Col. Owens, privately reproaches Roper for his inhumane treatment of the prisoner, Roper maintains that Bailey, who had stolen a horse to escape and then left the exhausted animal to die in the desert, deserved the punishment for his cowardice. One of the prisoners, Capt. John Marsh, visits Bailey in the hospital and warmly promises the young man that he will get him home. Later, Marsh and fellow prisoner Campbell caution an impetuous younger soldier, Cabot Young, against being too hasty to attempt an escape. The following day, Roper and Lt. Beecher lead a patrol in search of some overdue supply wagons. In the desert, they come across the charred remains of the wagons and find the bodies of the drivers staked to an anthill, victims of the vicious Mescalero Indians. That night, the soldiers come to the aid of a covered wagon that has been under Indian attack. The wagon's passenger, a beautiful Texan named Carla Forester, says she is on her way to Fort Bravo to visit Owens and his daughter Alice, who is soon to marry Beecher. The troops return to the fort, and Carla frankly expresses her interest in Roper, asking him to escort her to the dance the following night. At the dance, to which some of the Confederate officers have been invited, Carla dances with Marsh, her secret fiancé, and they discuss plans for his escape on the night of Beecher and Alice's wedding. Afterward, Carla returns with Roper to his quarters, where he shows her his treasured rose garden and speaks to her about his life. The following day, Roper insists on accompanying the women as they ride into town to buy a wedding dress for Alice. In the general store, Carla pays the proprietor, Watson, a Southern sympathizer, to equip her with horses and supplies, and arranges for him to come to the fort and smuggle the escapees out in his wagon. On the way back to the fort, Roper and Carla give in to their growing attraction and kiss. The following night, during the wedding festivities, Marsh, Campbell, Young and Bailey conceal themselves in Watson's wagon. Meanwhile, Roper declares his love for Carla and asks her to marry him. Carla, who has fallen in love with Roper, is shaken and asks to be alone. She then runs to the wagon and tells Marsh she is going with them. In the morning, the men are discovered missing, and the Rebel prisoners defiantly whistle "Dixie" at formation. Roper is sanguine about the escape until he learns that Carla is also gone. He sets out to bring the prisoners back, and Beecher, fearing that Roper might take revenge on Carla, insists on going with him. They ride to a nearby town, where Roper finds Bailey in a bar. Bailey, a sensitive poet, surrenders to Roper and admits that fear of Mescalero attacks prompted him to part ways with the others. With Bailey in tow, Roper and Beecher catch up with the fugitives on the road to Texas, but on the way back to Fort Bravo they are attacked by Mescaleros. Roper distributes guns among his captives, and both sides fight together against their common enemy. They survive the attack, but end up trapped in a gully without their horses. During the night, one of the horses returns, and Bailey takes it and flees. The Mescaleros launch a fresh attack the following day. Using spears to mark the perimeter of the gully, the Mescaleros direct a volley of arrows toward the helpless soldiers, leaving Marsh and Beecher badly wounded. Campbell and Young run out and tear down the markers, but they are shot to death by the Mescaleros. That night, Marsh tells Roper that Carla is in love with him. The following morning, Roper tells the others he wants to make the Indians believe he is the last one alive so they will end the standoff. After embracing Carla, Roper walks out in plain view of the Mescaleros, and is shot and wounded. Just then, Union troops ride to the rescue, led by Bailey, who rushes to the dying Marsh's side in time to say goodbye. The weary survivors return to Fort Bravo.