The novel begins with Addie Bundren, wife to Anse Bundren and mother of their children, on her deathbed. The rest of the family waits around for Addie’s impending death and vaguely discuss their eventual plans to cart their mother’s corpse forty or so miles to the town of Jefferson, where she has requested to be buried alongside her family. The oldest son, a level-headed carpenter named Cash Bundren, spends the days preceding Addie’s death outside her window, dutifully constructing a coffin. This gesture upsets Jewel, who thinks the rest of his family is vindictively rushing Addie to her death. Despite initial reservations from Anse, who believes Addie is going to die any minute, Darl and Jewel leave home to run an errand for their neighbor Vernon Tull. Anse’s fear comes true, and Addie dies just after the two leave. After Addie’s death, Anse orders his children to make preparations – Cash to finish the coffin and Dewey Dell to prepare the fish that the six-year-old Vardaman caught earlier that day. Vardaman cannot help but confuse his mother and the fish, as he understands that the fish is no longer alive, and hence explains Addie’s death through comparison. Yet Vardaman still does not have a full grasp of the material realities of death, and worries that his mother won't be able to breathe nailed into her coffin. In the night Vardaman drills holes in Addie’s coffin in an attempt to provide her with air. Inadvertently in the process, Vardaman bores holes in the face of Addie’s corpse. As the family members mourn and make preparations for their journey to Jefferson, Dewey Dell finds herself distracted by her potential need for an abortion, as she fears her recent intercourse with a farmer named Lafe got her pregnant.
Darl and Jewel return after the funeral service has already been held. Darl notices buzzards over the Bundrens’ home. With Darl and Jewel back home, the family begins to make preparations to leave for Jefferson. Anse repeatedly explains to himself, to the family, and to others, that they are traveling so far to fulfill Addie’s wish, though he also excitedly thinks about the fact that he will be able to buy a new pair of false teeth in town. As they prepare to leave, Cash obsesses over the fact that the coffin he so carefully built is unbalanced on the wagon, but the other family members ignore his meticulous request to balance it. Instead, Jewel charges in and carries the coffin onto the wagon by himself. Afterward, Jewel saddles up on his beloved horse and insists that he will follow the Bundrens as they ride in the wagon. Darl is angered by Jewel’s decision, and thinks to himself about how Jewel secretively worked each night to buy himself the horse, and how Addie supported it, making the other children do Jewel’s chores for him as he worked.
The Bundrens set off on their journey and stay with a local farmer named Samson and his family. Samson tells the Bundrens that the bridge that they plan to use to get over the river has been submerged from recent rains, and that they should re-route their journey. The Bundrens attempt to cross the river at a ford, but as they try to cross a log comes down the river on the current and knocks the coffin off the wagon, breaks Cash’s leg, drowns the Bundrens’ team of mules, and throws Cash’s prized collection of tools into the water. Jewel, with help from the Bundrens’ on-looking neighbor Vernon Tull, retrieves the coffin from the flood and dives down into the river to rescue Cash’s box of tools.
The narrative is interrupted most overtly in the fortieth section, narrated by Addie – either at an earlier point in time or from her position as a corpse. In this section, Addie muses on her mistrust of language, her lack of passion for Anse, her wariness and sense of regret over having had children, and her extramarital affair with the local minister Whitfield.
Meanwhile, back on the journey, Cash faints from the pain of his newly broken leg but does not make a peep. Jewel brings Cash a horse-physician to set Cash’s leg in splints, claiming that horses and humans are quite alike. Cash’s stoicism becomes almost absurd, as the family continues to ride for days in their decrepit wagon in the heat, marked by the stench of Addie’s corpse. The family decides to spend the night at the home of another local farmer named Armstid. There, Anse rides off on Jewel’s horse to purchase a new team of mules; Anse ends up giving a mortgage on some farm machinery, some of Cash’s savings, some of his own savings (for new teeth) – and finally, Jewel’s horse. Jewel is shocked but permits his father’s actions nonetheless.
The Bundrens eventually reach the town of Mottson, where Jewel immediately gets in an altercation with a local resident about the putrid odor coming from the wagon. Darl calms everyone down and the family continues on its way. In town, Dewey Dell goes to the pharmacy to buy an abortion drug, but Moseley, the town pharmacist, tells her to get a marriage license instead. Before leaving Mottson, Darl mixes cement to create a cast for Cash’s leg, though the cast only ends up making things worse. The Bundrens are challenged by the Mottson town marshal, who complains about the stench of Addie’s corpse and advises Cash to see a doctor.
That night, the family reaches yet another local farm owned by a farmer called Gillepsie. After telling Vardaman that Addie has spoken to them of her desire to flee from human sight, Darl burns down Gillepsie’s barn in order to burn Addie’s coffin and put an end to the Bundrens’ farcically hellish quest to bring her to Jefferson. Vardaman sees Darl’s actions but Dewey Dell advises him to keep it a secret. As the barn is furiously ablaze, Jewel rushes in to rescue Gillepsie’s cattle and other animals – and most importantly, to retrieve Addie’s coffin from the fire.
Finally, the Bundren family reaches Jefferson. Anse goes into a house to borrow two spades with which to bury Addie. The family is later confronted by Gillepsie, who knows somehow that Darl was responsible for burning down his barn. In order to avoid being sued, the Bundrens claim Darl to be insane, and ship him off to an institution in Jefferson. Dewey Dell tries her hand once again at getting an abortion drug, but the pharmacy clerk forces her to have sex with him and gives her some medicine that she is sure is fake. The family prepares to leave Jefferson, though Anse keeps claiming to be busy with various things, delaying them. Finally, on the last pages of the novel, Anse, now smiling with his new false teeth, introduces his children to the new “Mrs. Bundren,” the woman who lent him the spades just days before.