For centuries, the Lost Santiago Mine in the Dead Horse Mountains of Texas was one of the great mysteries of the Southwest. Chisos Owens is hired by Anse Hawkman to protect his extensive holdings, and he not only finds the mine, but he also discovers Elgera Douglas, who rides a magnificent Morgan palomino and is known as Senorita Scorpion. When Owens learns the story of the Douglas family and their quest to protect the Lost Santiago Mine, he joins forces with Senorita Scorpion against Anse Hawkman.