Luke Brazo is on the trail of a lone wolf, nicknamed Lobo, that has been harassing farmers around Dodge. But Luke will prove to be more of a lone wolf and just as dangerous as any animal. 

Down on his luck, a widowed farmer is unable to get a loan from his brother-in-law, a banker in Dodge City. The two briefly argue. The farmer's son and daughter, however, go back to the bank, cause a commotion and steal an envelope full of money. Marshal Matt Dillon is out of town, leaving Festus in charge of investigating the incident. The farmer is arrested for the robbery. Upon hearing from his children that they took the money, he forbids them from telling the law; he feels he'll only be using his children as scapegoats. A short time later, the children run away and encounter Matt.