In "The Straight Story," a luminous oddball odyssey directed by David Lynch, an old man rides a lawnmower across Iowa into Wisconsin to visit his estranged, gravely ill brother. Mr. Lynch's road movie, traveling two-lane highways at single-digit speeds, dares tobe as direct as it is leisurely; to be sweet in its celebration of American generosity (this heartland is an irony-free zone where people still extend kindness to strangers); and to be ardent as well as rueful and tender in its portrait of old age. Except for a few interludes along the way, the director distances himself from the eeriness and darkness that has distinguished his best work, including "Eraserhead," "The Elephant Man" and "Blue Velvet," as well as his last feature, "Lost Highway," a turgid road movie with no map. In doing so, he has made the most deeply affecting film of his career–how's that for a neat irony?–and given audiences a gift of enduring beauty.

"The Straight Story," written by John Roach and Mary Sweeney, was inspired by a newspaper account of an Iowan named Alvin Straight, who took just such a journey a few years ago. In the film Alvin is played by 79-year-old Richard Farnsworth, who, as a stunt man for Cecil B. DeMille, drove chariots in "The Ten Commandments." It's a quietly magnificent performance that transcends dramatic technique, but Mr. Farnsworth is far more than a gifted primitive; he was the seductive gentleman bandit in Philip Borsos's 1982 "The Grey Fox." By now he's old enough, thank you very much, to make Alvin Straight's various ailments painfully convincing; hips, eyes, heart and lungs are all disaster areas in need of emergency aid, which Alvin is too proud to accept. Yet Mr. Farnsworth's zestful spirit backlights the hero's weathered face, full of wary expectancy, and sustains notes of love and hope–and firm resolve–in his reedy voice.

Since the movie rests on such a peculiar vehicular premise, it's fair to ask why Alvin, who has lost his drivers license, can't take a bus or ask his mildly retarded daughter (Sissy Spacek in a lovely, tough-minded performance) to give him a ride in her beat-up old sedan. The answer has less to do with practicality than with dogged determination, plus a need for penance after what he considers a wayward life; he wants to do it his own way, which means the hard way. It's also fair to ask if Alvin reaches the end of the road in time to make peace before his brother dies. Suffice it to say that the climax is worthy of the journey, a scene of perfect tact and exquisite intensity.

And what a journey it is, chugging past fields of wheat and corn at harvest time (the beauty of America seen by the masterly British cinematographer Freddie Francis, who also shot "The Elephant Man") or past friendly Iowans waving hello (and recalling, without sinister counterpoint, the firemen waving in "Blue Velvet"); rolling periously close to a burning house (but again no underlying omninousness, it's a firemen's practice drill), or through severe storms (which Alvin contemplates with serene satisfaction). This slice of Americana is all white, an omission that misrepresents the territory, though the film accurately shows America's rural population as aging, if not up there with Alvin. Among the bumpy interludes are an intrusive set piece involving a serial deer slayer, and some arch comedy with goofball twins. But the bumps are small and the pleasures are many: a touching encounter over a campfire with a runaway girl; a stirring one, at a bar, with a fellow World War II vet; a funny glimpse of old married linked by complicity and telepathy; a column of cyclists whizzing by, near-silent peddlers in the parade of life.

Advance publicity has portrayed "The Straight Story" as a strange anomaly–David Lynch taking a detour into wholesomeness for Disney. In fact, the production came together with French funds, quickly and easily, once Mr. Lynch read the script and decided to do it. Only later was the film picked up by Disney, in what now seems like a natural match between product and distributor. But the match between material and director is not unnatural. Born in the Big Sky state of Montana, Mr. Lynch has always been a romantic, notwithstanding the weirdness or bleakness of his themes; has never evinced much interest in irony; has always loved a measured pace. As far as I can see, he simply spotted a great story and embraced it. So will you.