A New Hampshire deputy constable named Clendon Macmillan comes to Laredo with 9 years of experience, intending to improve the quality of the average Ranger. He would like to apply his modern law enforcement techniques to what he refers to as "" the most primitive law enforcement organization in the country - the Texas Rangers."" He is sent out with Reese, Chad, and Joe to track Running Antelope and Linda Little Trees. Chad and Joe take a fiendish delight enjoying the fact that no man has ever rubbed Reese the wrong way as easily as MacMillan does. They arrive at a town just raided by Running Antelope and find Linda Little Trees in jail. While the rest are having steaks with the Marshall Little Trees talks MacMillan into releasing her, saying she will take him to their hideout. He is taken prisoner and rescued by Reese, Chad and Joe. Upon their return to Laredo Parmalee offers MacMillan the toughest Ranger assignment ever but MacMillan declines saying he's needed back in New Hampsh

New ranger Cotton Buckmeister is assigned by Judge Larkin to return a strongbox of official documents to Uvalde. Chad and Joe are to accompany him. Judge Ike Macallum ruthlessly rules Uvalde and has illegally brought charges against many people in order to blackmail them. So both Macallum victims and his henchmen are after the strongbox. During the journey Chad and Joe discover that Cotton also has an interest in the strongbox as he is ""wanted"" for breech of promise when he refused to marry Judge Macallum's sister Ada. A shootout occurs before Parmalee can arrive with Judge Larkin. Joe ends the gunfight by blowing the strongbox up with dynamite. All of the documents are destroyed except one - Cotton's. Court is held and Cotton is found guilty and Chad and Joe are appointed as supervisors.