In the late sixties and early seventies, the anti-establishment feelings engendered by opposition to the Vietnam War resulted in a lot of movies that equated crime with freedom. Somehow, those who broke the law and flouted convention were better than those who obeyed the law, held down regular jobs, and led respectable lives. Rancho Deluxe is clearly in that mold.
In particular, Jack (Jeff Bridges) and Cecil (Sam Waterston) are small-time cattle rustlers, who kill a cow every now and then and sell the meat. John Brown (Clifton James) owns the cattle and wants to catch whoever is stealing them. When Jack and Cecil steal Brown’s prize bull and ransom him for a great deal of money, they begin to think about making a bigger haul.
Meanwhile, Curt (Harry Dean Stanton) and Burt (Richard Bright), ranch hands who work for Brown, figure out that Jack and Cecil are the rustlers. Instead of telling their boss, they end up agreeing to work with Jack and Cecil to make a big score. And while this is going on, Brown hires Henry (Slim Pickens), a senile old detective who can hardly walk, to solve the crime. He is so feeble he has to be helped by his niece Laura (Charlene Dallas), who is an innocent do-gooder. At least, so it appears. In reality, Henry is neither senile nor crippled, and Laura is not his niece, but his partner. Henry knows that a big-time heist is always an inside job, and he arranges to have Laura seduce Curt and get the information from him about the caper. They foil the thieves, who are sent off to prison.
But as I said, this movie was made back when criminals were romanticized as free spirits. Consequently, it would not do to send them to a real prison. Instead, they are sent to a ranch penitentiary, where they ride the range herding cattle for the state of Montana, so it really does not seem like punishment at all, but just another way of being free.