In pre-Civil War Texas, naive Karl Westover (Gary Busey) accidentally kills his brother-in-law and heads to Mexico to escape the consequences. Along the way, he encounters Barbarosa (Willie Nelson), who is also on the run. Barbarosa teaches Karl survival skills for the desert -- and how to rob. In their journey from Texas to Mexico and back again, the two men are captured by outlaw Angel Morales, and pursued by Don Braulito (Gilbert Roland), who wants Barbarosa dead.