In a small New England town, Iris King’s purse is stolen on her bus ride home from work. Iris chases the thief while Stanley Cox, another bus rider, follows. In an alley, Stanley comes to Iris’s aid as the thief escapes. Iris complains that she just lost her paycheck, but Stanley argues that she should not have risked her safety over money. Stanley recognizes Iris from the bakery where they both work, but she admits she never noticed him before. That night, Iris serves dinner to her two children, Richard and Kelly; her sister, Sharon; and Sharon’s boyfriend, Joe. Although Sharon claims she has no money to contribute to the household, she angrily accuses Joe of stealing her secret stash of cash when she sees him drinking beer. Joe slaps Sharon’s face, and Jane sends Richard and Kelly outside. Later, while recalling Iris’s devotion to her late husband, George, Joe remarks that he chose the wrong sister. At the bakery, Iris works on an assembly line, adding whipped cream to cakes. That evening, she runs into Stanley at a shoe repair shop, and is amused when he refuses to sign a ledger in exchange for his shoes. Another day, Stanley runs into Iris at the bus stop and offers her a ride home on his bicycle. On the way to Iris’s house, Stanley reveals that he lives with his father, has never been married, and spends most of his time alone. The next time he sees Iris, Stanley, who works at the bakery’s cafeteria, serves her extra potatoes. The two run into each other again at a laundromat, and Stanley suggests they eat Chinese takeout from the restaurant next door. As they share a meal outside, Iris explains that her husband died eight months before, but his life insurance company dropped him, so she received no money when he died. Iris says she would love to go to Boston, Massachusetts, and stay at a nice hotel, and Stanley replies that he prefers the countryside, describing a six-day camping trip he once took alone to the Grand Canyon. Stanley confesses that he watches Iris because she stands out, but the conversation ends abruptly when she asks him to read his fortune cookie. One day at the canteen, Iris asks Stanley for the bottle of Tylenol behind the counter. Unable to read the labels on various medicine bottles, Stanley offers her the wrong pills and Iris deduces that he is illiterate. Stanley’s boss appears and reprimands Stanley for lost inventory, but Iris defends her friend by announcing that Stanley cannot read or write. After work, Iris follows Stanley to a bar and defends her actions, saying that he was headed for trouble. She asks why he does not do something about his illiteracy, and he storms out. Stanley is fired from the bakery. He takes menial day jobs to make money but is forced to admit his father to a state-run retirement home after losing his apartment. Meanwhile, Iris discovers that her teenaged daughter Kelly is pregnant and warns the girl that having a baby is a serious responsibility. Soon after, Stanley is devastated to learn that his father has passed away. He nervously approaches Iris outside the bakery and asks if she will teach him to read. She agrees and they begin working together. One night, Stanley shows up at Iris’s house drunk, and she asks him how he got by in school without learning to read. Stanley explains that he moved around a lot with his father and kept a low profile as a student. During one of their lessons, Iris receives a phone call from a man asking her on a date, which Stanley overhears. Iris rejects the offer, and, after she hangs up, Stanley inquires about her dating life, which she admits is nonexistent. Stanley later takes Richard for a walk and commiserates with the boy, revealing that he recently lost his father. Richard responds that his father was sick for a very long time. Iris becomes irritated during one of Stanley’s lessons because he did not do his homework. She admits to being sexually frustrated, and Stanley confesses that he has wanted to make love to her since he first saw her. Iris remarks that Stanley would need to take a blood test first, and he agrees, then offers to do her ironing so she can rest. Stanley gets a job as a short order cook and studies while he works. One day, Iris tests Stanley's progress by giving him a street map and instructing him to meet her at a specific street corner. Unable to decipher the map, Stanley throws it away in frustration and refuses to speak to Iris once he finds her. Sometime later, Iris and Richard encounter Stanley at the park, but he says she will not be seeing him again. Iris seeks out the garage where Stanley lives. She suggests Stanley find another teacher, but he insists that reading was too hard for him. Noticing a large contraption that Stanley is working on, she discovers that he has invented a machine that rapidly cools cakes. Stanley comments that his illiteracy has allowed him plenty of time to invent things. They begin seeing each other again for reading lessons, and when Kelly goes into labor, Stanley joins Iris in the hospital waiting room. Sometime later, Stanley cooks dinner for Iris’s family as Kelly tends to her baby. Noticing that Stanley’s jacket is frayed, Iris offers him her husband’s jackets, and he accepts but reminds her that he is a different man. Expressing his desire for her, Stanley vows to spark a romance with Iris by spending time and money on her. One day, Kelly joins Iris on the assembly line at the bakery, and Iris warns her daughter that the job will lead nowhere. When Iris and Stanley finally make love, Iris cries and he leaves in frustration. Sometime later, Stanley paces outside the house and Iris invites him in. She shows him a letter she wrote during their separation, and Stanley reads it aloud. Iris is amazed by his progress, and they go to the library, where he proudly reads aloud from several books, disturbing the other patrons. He takes Iris to celebrate at a hotel in Boston, where he proclaims his love. A company in Detroit, Michigan, hires Stanley to work as an engineer after taking an interest in his cake-cooling device. Stanley tells Iris that the company will help him obtain a patent, and promises to write her letters while he is away. Iris receives frequent letters from Stanley, who returns unexpectedly one night and asks her and her family to move into a six-bedroom house he just bought in Detroit. Overjoyed, Iris reminds Stanley that her family is a demanding group before accepting his invitation.