Young newlyweds Paul (Harry Treadaway) and Bea (Rose Leslie) travel to remote lake country for their honeymoon where the promise of private romance awaits them. Shortly after arriving, Paul finds Bea wandering and disoriented in the middle of the night. As she becomes more distant and her behavior increasingly peculiar, Paul begins to suspect something more sinister than sleepwalking took place in the woods.
The Texas Rangers chase down a gang of outlaws led by Butch Cavendish, but the gang ambushes the Rangers, seemingly killing them all. One survivor is found, however, by an American Indian named Tonto, who nurses him back to health. The Ranger, donning a mask and riding a white stallion named Silver, teams up with Tonto to bring the unscrupulous gang and others of that ilk to justice.