In 1880, Frank Ross, of Yell County, Arkansas, is murdered and robbed by his hired hand, Tom Chaney. Ross’s young daughter, Mattie, travels to Fort Smith and hires aging U.S. Marshal Reuben “Rooster” J. Cogburn to apprehend Chaney. Mattie earns enough to pay his fee by horse trading. Meanwhile, Chaney has taken up with outlaw “Lucky” Ned Pepper in Indian Territory.^[a]

Young Texas Ranger La Boeuf is also pursuing Chaney and joins forces with Cogburn, despite Mattie’s protest. The two try, unsuccessfully, to ditch Mattie.

Days later, the three discover horse thieves Emmett Quincy and Moon, who are waiting for Pepper at a remote dugout cabin. Cogburn captures and interrogates the two men. Moon is shot in the leg during the capture, and Cogburn uses the injury as leverage for information about Pepper. Quincy slams a knife down on Moon’s hand to shut him up, severing four of his fingers, then kills him. Cogburn shoots Quincy dead. Before dying, Moon reveals Pepper and his gang are due at the cabin that night for fresh mounts.

Rooster and La Boeuf lay a trap. Upon arriving, Pepper is suspicious and draws La Boeuf’s fire, which blows cover of the planned ambush with a premature shot, inadvertently killing Pepper’s horse. A firefight ensues, during which Cogburn and La Boeuf kill two gang members, but Pepper and the rest of his men escape unharmed. Cogburn, La Boeuf, and Mattie go to McAlester’s store with the dead bodies. Cogburn tries, unsuccessfully, to persuade Mattie to stay at McAlester’s.