Because of his drunkenness and questionable use of firearms, aging one-eyed (wearing a distinctive black eye patch) United States Marshal Service Rooster Cogburn (character) (John Wayne) in the Indian Territory (future Oklahoma) has been stripped of his badge by Judge Parker (John McIntire) at the territorial capital of Fort Smith, Arkansas for excessive violence fatness and drunkenness, complaining he had "gone to seed". But he's given a chance to redeem himself after a shipment of highly explosive nitroglycerine is stolen from a transporting troop of United States Army cavalry. Rooster agrees and eventually tracks the outlaws, led by Hawk (Richard Jordan) and his gang, along with Rooster's former scout Breed (Anthony Zerbe - who had earlier betrayed the Cavalry troop escort to be ambushed at a creek crossing by Hawk's cutthroats), to a church mission at the remote settlement of Fort Ruby in the Indian Territory. The village had been overrun earlier by the gang who camped overnight plying the Native Americans in the United States with liquor and gambling, who then killed an elderly missionary preacher who protested, Rev. George Goodnight (Jon Lormer) and a number of the local Indians. The Reverend's spinster daughter, Miss Eula Goodnight (Katharine Hepburn), wants to join Marshal Cogburn to track the criminals down, becoming his unwilling partner along with her student Wolf, the son of one of the deceased Indians, who aspires to be one of the first Indian lawmen and United States Marshal.