At the age of sixty-six, Warren R. Schmidt retires from his job as assistant vice-president at the Woodmen of the World insurance company in Omaha, Nebraska. A man whose identity derives from his position at work and status as wage earner for his wife Helen and grown daughter Jeannie, Warren faces a life of leisure with bewilderment. At his retirement party, he responds to the laudatory toasts from his coworkers by fleeing into a nearby bar to drink alone. Later, he receives a congratulatory phone call from Jeannie, who is engaged to Randall Hertzel, a waterbed salesman whom Warren considers undeserving of his daughter. The next morning, Helen fixes him breakfast in their Winnebago, which they plan to drive across the country, but Warren remains indifferent to everything until he finds himself responding to a television advertisement for Childreach, an organization that sponsors needy children in Third World countries for a donation of twenty-two dollars per month. After a few more days of puttering, he puts on a suit and returns to his office, where his replacement cheerfully indicates that Warren’s presence is completely unnecessary. Dejected, Warren returns home, where he finds a packet from Childreach with a photo of his “foster” child, Ndugu Ombo, a six-year-old Tanzanian boy, and a request that he send Ndugu a letter. As Warren begins writing a description of his life, his true feelings pour out about the “snotty kid” who has replaced him at work, his failure to achieve his dreams, his beloved daughter’s upcoming marriage to an idiot and his wife’s irritating, controlling habits. After running an errand, however, Warren returns to find Helen dead of a blood clot, and in his grief realizes how much he loved her. He remains busy over the next few days planning the funeral and consoling Jeannie, who arrives in Omaha with Randall. Randall’s clumsy, cloying attempts at kindness frustrate Warren, especially after the young man offers to "invest" Warren’s money in a pyramid scheme. When Jeannie is ready to leave, Warren, who is unaccustomed to being alone, tries desperately to induce her to stay and postpone her wedding, at one point even lying that Helen did not approve of Randall. Jeannie, shocked but unconvinced, responds by questioning Warren’s substandard casket choice. After she leaves, Warren wanders around his increasingly disarrayed house, expressing in a letter to Ndugu his grief and fear that he will soon die. While wistfully exploring Helen’s closet, Warren unearths a box containing love letters to her from his best friend, Ray Nichols. In a fury, he discards all of Helen’s clothes and confronts Ray with the letters, despite his friend’s plea that the affair ended thirty years ago. Newly invigorated, Warren enacts his sense of freedom by urinating while standing, an act Helen had forbidden. He then packs up the Winnebago and leaves for Denver, hoping to spend more time with Jeannie. When he calls her with his plan, however, Jeannie firmly insists that he stay away until a few days before the wedding. Chagrined, Warren heads to his hometown of Holdrege, Nebraska, only to find that his childhood house has been replaced by a tire store. He goes on to his alma mater, Kansas University, along the way writing to Ndugu, urging the boy to follow in his footsteps and pledge a fraternity. At a campground in Kansas, John and Vicki Rusk, Canadians staying in the adjoining campsite, invite Warren for dinner. He enjoys their hospitality, but when John leaves to buy beer, Warren mistakes Vicki’s empathy for a flirtation and attempts to kiss her. Vicki responds in horror, prompting Warren to flee the campground and drive all night. On the road, he attempts to leave a conciliatory phone message for Ray, but the answering machine malfunctions. Despondent, Warren spends the night atop the Winnebago, where he asks Helen for forgiveness and sees a shooting star that he assumes is a sign. He awakens with a clear sense of purpose: to put a stop to Jeannie’s wedding. With this in mind, Warren heads to the Denver home of Randall’s mother Roberta. Roberta’s earthy gregariousness disturbs Warren, especially after she voices her pride in Randall’s “sensitiveness,” which she feels derives from her having breastfed him for five years. They have dinner with Jeannie, Randall and his relatives, including his verbose father Larry, Roberta's ex-husband, during which Warren despairs further at Jeannie’s choice for a new family. He finally corners his daughter on the porch after dinner and reveals that he does not approve of her marriage. Jeannie, who loves her father but considers him distant and difficult, orders him either to support her or leave. That night, he throws his back out while sleeping on Randall’s waterbed, infuriating Jeannie further. Roberta nurses Warren with soup, not realizing that he is pained further by her candid discussion of Jeannie’s sex life with Randall. Before the wedding rehearsal that night, Roberta gives Warren a prescription pain reliever that keeps him pleasantly doped until after dinner. He then enjoys her hot tub, but after she joins him, naked, and places her hand on his leg, Warren retreats to the Winnebago. He endures the wedding the next day without comment, and when it is his turn to give a speech, falters briefly, but finally, turning to his grateful daughter, delivers a moving speech invoking Helen and her blessing upon the marriage. As he drives back to Omaha, Warren composes a letter to Ndugu stating that he has failed, not only in his quest to save Jeannie but in his life as a whole. He questions if he has made any difference to anyone. At home, a despondent Warren leafs through his mail, where he finds a letter from Ndugu’s caretaker, Sister Nadine Gautier. Sister Nadine writes that Ndugu, an orphan who can neither read nor write, has enclosed a drawing for his “foster father." The picture, which depicts a man holding the hand of a small boy under a shining sun, causes Warren to weep with the sudden understanding that he has made a mark on at least one life.