Alvin Straight (RICHARD FARNSWORTH) is a 73-year-old man who hasn't spoken to his brother, Lyle (HARRY DEAN STANTON) in more than ten years due to harsh words spoken at their last meeting. A simple, but proud and stubborn man, Alvin lives with his mentally slow adult daughter, Rose (SISSY SPACEK), and hates that his health is progressively deteriorating.
When he gets a call that Lyle has had a stroke, Alvin decides to swallow his pride and go and visit him. The only problem is, Lyle lives in Mt. Zion, Wisconsin, several hundred miles from Alvin's home in Laurens, Iowa, and due to his failing eyesight, Alvin has neither a car nor a driver's license.
Not letting that or his bad hips deter him, the WWII veteran decides he'll simply drive his riding lawn mower through the farmlands and across the Mississippi. When his first attempt fails due to mechanical problems, Alvin takes his limited cash and buys a 1966 John Deere mower. With a stocked trailer hitched behind it, Alvin sets off.
Traveling at five miles an hour and camping out overnight, Alvin's trip soon turns into a several week odyssey where he meets various people who touch or are touched by his aged wisdom. They include Crystal (ANASTASIA WEBB), a young and pregnant runaway, a woman (BARBARA ROBERTSON) with an unfortunate penchant for hitting deer on her commute, a middle-aged couple, Danny (JAMES CADA) and Darla Riordon (SALLY WINGERT) who help him when his mower breaks down, and Verlyn Heller (WILEY HARKER), a fellow WWII vet.
Proudly refusing rides from anyone he meets and as the weeks of fall pass by as he ever so slowly nears Mt. Zion, Alvin not only hopes that his brother is still okay, but that they can reconcile their differences and spend some time together as they once did, staring up in into the star-filled night sky.