Buford Pusser (Joe Don Baker), at his wife Pauline's (Elizabeth Hartman) behest, retires from the professional wrestling ring and moves back to Tennessee to start a logging business with his father, Carl Pusser (Noah Beery, Jr.).
With a friend, he visits a gambling and prostitution establishment, the Lucky Spot, and is beaten up after catching the house cheating at craps. Pusser is seriously injured with a knife and receives over 200 stitches. He complains to the sheriff but is ignored, and soon becomes aware of the rampant corruption in McNairy County. Later, working at his dad's lumber mill, Pusser makes a club out of a tree branch. Late one night, Pusser waits until after the Lucky Spot is closed, and beats up the same thugs that left him for dead. The next day, Pusser is arrested and represents himself at trial. At one point, he rips off his shirt and shows the jury his scars. He informs them that "If you let them do this to me and get away with it, then you're giving them the eternal right to do the same damn thing to any one of you!" The jury finds Pusser not guilty, and he decides to clean up the county and runs for sheriff. Buford Pusser wins, and becomes famous for being incorruptible, intolerant of crime, and for his array of four-foot hickory clubs which he uses to great effect in dispatching criminals and destroying their clandestine gambling dens and illegal distilleries.
Some residents praise Buford Pusser as an honest cop in a crooked town; others denounce him as a bully willing to break some laws to uphold others. Pusser is attacked several times, and finally he and Pauline are ambushed in their car. Pauline is killed and Pusser is seriously injured. He is admitted to the hospital after being shot and while still in a neck and face cast, attends his wife's funeral with his family. Afterward he rams a sheriff cruiser through the front doors of the Lucky Spot, killing two of his would-be assassins.
As he leaves with two deputies, the townspeople arrive and begin throwing the gambling tables out into the parking lot. They light a bonfire as an overwhelmed Pusser wipes tears from his eyes.

Question: Why does Buford run for sheriff?
Answer: To try and clean up the town.
Alternative answer: The town is corrupted