As elderly people go about their day in Manhattan, Harry walks along a sidewalk with his tabby cat Tonto on a leash, quoting Shakespeare's "King Lear" as he goes. Harry stops in at a grocer, buys some good food for his cat, and jokes that his sexual days are over.Next Harry meets his old friend Jacob on a bench, and tells him that his apartment building is being torn down to build a parking lot. Jacob complains about capitalists, and reassures Harry that he could always move in with him.On the way home, a kid tries to steal Harry's groceries and knocks him down. Harry is helped up by Leroy, his building super.Harry gets into his apartment and talks to Tonto, lamenting that he's been mugged four times in the past year, and that the whole city is getting run down.Some time later, police show up to forcibly remove Harry and his furniture from the building. Harry continues to spout "King Lear" while his son Burt arrives to pick him up.Harry goes to live with Burt and his wife and two grown sons in the suburbs. His younger grandson, Norman, has taken a vow of silence, leading to obvious tension with his brother and parents. Harry later asks Norman for the books that explain his beliefs.Harry goes back to his familiar bench to talk with Jacob, and they both agree it's been a long time since either has been with a woman. Jacob reminisces about his first sexual encounter with a servant girl when he was 14.Harry invites Leroy to dinner at Burt's house, and he plays the piano while Leroy dances to the tune. Leroy later comments that he lives with his 90-year-old mother and can't find a new job, which leads Burt's wife to question why Harry is not getting help from his two other kids.Knowing that he is a burden to Burt, Harry goes to look for his own apartment, but finds that the place he wants will not take cats. He then tells Burt he is going to Chicago to visit Shirley, Burt's sister, but before he leaves he stops at a city morgue to identify the body of Jacob, who has died with no relatives. Harry cries after recalling Jacob's story of losing his virginity.Burt takes Harry to the airport, but Harry soon learns that he can't go through security with Tonto, so he takes a cab to get a bus. Along the route, Harry asks the bus driver to stop so that Tonto can relieve himself, whereupon the cat runs away across a cemetery. The bus driver leaves Harry behind with his luggage, and when Tonto returns, Harry scolds him.Harry walks to a used car lot and buys an old Chevy for $250. He then checks into a motel and calls Burt to tell him what has happened, realizing in the process that his driver's license expired in 1958.Harry drives west rather slowly, with Tonto on the dashboard, recalling how he wanted to drive across the country when he was younger, but his wife and kids came along. He remembers they had many good times though. He confesses to Tonto that he has a great fear of pain, and that when he dies he would like to go quickly rather than the slow way his wife Annie died.Harry picks up two young hitchhikers, one of whom soon gets another ride, while the other a girl named Ginger continues west with Harry. She claims she is 16, and is running away from home to a commune in Boulder.Harry and Ginger get a motel for the night, and after she comes out of the bathroom half-naked, Harry is prompted to recall the first girl he loved, Jessie, whom he has not seen in 50 years. Ginger suggests that they go to see her, even though it's out of their way, and they eventually find her in a nursing home.At first Harry thinks Jessie remembers him, but her thoughts are marked by senility; she calls him Alex yet remembers his wife Annie. Then she suddenly asks Harry to dance, which they do while Ginger looks on.Harry and Ginger make it to Chicago, where Shirley runs a bookstore. Harry is surprised to see Norman there, who has been sent in advance by Burt to meet him, and who is now talking. Shirley is curt with Harry and Ginger, and is mourning the end of her fourth marriage.Shirley and Harry go for a walk by the edge of Lake Michigan, and she encourages him to return to teaching; he says he is too old. They have an awkward exchange, and agree to be more civil to each other.Harry drives on with Norman and Ginger, reaching Arizona. Harry calls Burt and has Norman explain his situation, which does not go over well. Harry tells Burt he is moving on to Los Angeles to visit Eddie, his other son, while Norman tells Burt that he is going with Ginger to Boulder.Harry thus gives the car to them, and wonders off to a motel, where he meets a traveling salesman of natural health products. While the man gives Harry a shoulder rub, he sells him a blender he does not need.Harry hitchhikes and is picked up by hot redhead in convertible. She reveals she's a high-priced hooker, and asks Harry how long it's been since he had sex. He stammers, saying he does not think he's up to it and can't afford her, but when he mentions he has $100, she drives off the road and takes him up a hillside.The hooker drops Harry off at a Las Vegas casino, where he has some drinks. A man at a craps table gets mad at him for cooling his win streak. Harry goes outside to give Tonto some milk, and begins to urinate against the building, whereupon police arrest him.Harry wakes up in jail with a native Indian named Sam Two Feathers. Harry offers him the blender he recently bought, and Sam gives him a necklace in exchange. Harry asks Sam if he can cure ailments, and in exchange for relieving Harry of the bursitis in his shoulder, Sam selects a pair of Harry's underwear.Harry finally makes it by bus to L.A., and walks along Hollywood Blvd. with Tonto, until his son Eddie drives by to pick him up. Eddie acts as if he's been living off his real estate deals, but when they get to his apartment, he confesses to his father that he is broke.Eddie cries in shame, and Harry consoles him that they will somehow find a way to help each other financially. Harry can provide some money for now, he says, but he wants Eddie to get on with his own life.Harry goes to the beach and enjoys a game a chess, during which Tonto suddenly does not look well.Harry takes Tonto to an animal hospital, and says goodbye.Harry goes to the beach to write a letter to Leroy, telling him that Tonto passed away at the age of 11, or 77 in human years. A woman named Celia, escorting many cats, comes to sit next to Harry, openly flirting with him. She soon suggests that they run around together, but Harry is distracted when he sees a tabby cat that looks like Tonto.Harry follows the cat out onto the beach and pets it. There he sees a little girl building a sandcastle in the sunset, and he joins her.