Watch Rio Grande for Free: How to Stream the Movie Online at 123Movies. . Lt. Col. Kirby Yorke is posted on the Texas frontier to defend settlers against depredations of marauding Apaches. Col. Yorke is under considerable stress by a serious shortage of troops of his command. Tension is added when Yorke's son (whom he hasn't seen in fifteen years), Trooper Jeff Yorke, is one of 18 recruits sent to the regiment.