Carter "Doc" McCoy (McQueen), an incarcerated criminal, is suffering from the isolation of prison life in Texas. After being denied parole, he sends his wife Carol (MacGraw) to do whatever's necessary to make a deal with Jack Benyon (Johnson]), a corrupt businessman in San Antonio.
Benyon has Doc paroled on the condition that he take part in a bank robbery with two of his minions, Rudy (Al Lettieri) and Frank (Bo Hopkins). A guard is killed and Rudy attempts a doublecross, shooting Frank and drawing a gun on Doc, but a prepared Doc beats him to the draw and shoots Rudy several times.
Doc meets with Benyon to divide the money. Benyon also attempts to doublecross him before being shot and killed by Carol. It is clear to Doc now that Carol had to sleep with Benyon in order to guarantee his release from prison. Angry and taking it out on her, Doc gathers up the money and the couple flees for the border in El Paso.
A bloodied Rudy, having secretly worn a bulletproof vest, is still alive. He forces a rural veterinarian named Harold (Jack Dodson) and his young wife Fran (Sally Struthers) to treat his injuries, then kidnaps them in order to pursue Doc and Carol.
Meanwhile, Benyon's brother Cully (Roy Jenson) and his thugs also go after the McCoys. Doc and Carol fight over her indiscretion with Benyon. At the train station, a shifty con man copies a locker key from Carol and lifts their bag of money from a locker. Doc follows the thief onto a train and forcefully takes it back. The injured con man and several witnesses are taken to the police station where they identify Doc's mug shot.
Now recognized wherever they go, the McCoys are forced into several shoot-outs and chases with the police. They escape by hiding in a trash bin, only to end up in the back of a garbage truck and dumped at the local landfill. Filthy and frustrated, they debate whether to stay together or split up. They decide to see things through.
Rudy's mutual attraction to the veterinarian's wife Fran leads to a sexual relationship in front of her husband. Humiliated, the vet hangs himself in a motel bathroom. Rudy and Fran move on, barely acknowledging the suicide.
They arrive first at an El Paso hotel used by criminals as a safe house, threatening the hotel's manager. Doc and Carol are given a room on the same floor and ask for food to delivered, but the manager says he is working alone and can't leave the desk. Doc eventually realizes that the manager has sent away all of his family, something that as an alcoholic he wasn't likely to do. He urges Carol to get dressed fast so they can get away.
Fran and an armed Rudy come to their door. Doc, peering from another doorway, is surprised to see Rudy alive. He sneaks up from behind and knocks out Rudy, then does the same to the screaming Fran.
Cully and his thugs arrive just as the McCoys descend the stairs. A violent gunfight ensues in the hotel's halls and stairwell. Doc and Carol kill all of Cully's men and flee via the fire escape. Rudy comes to his senses and follows them, but Doc shoots and kills him.
With the police en route, the couple hijacks a pickup truck and force its driver, a cooperative cowboy (Slim Pickens), to take them to Mexico. After crossing the border, Doc and Carol pay the cowboy $30,000 for his truck, which isn't worth anything close to that. Overjoyed, the cowboy walks back toward El Paso while the couple drives on into Mexico to a new life.