The Bundren family live on their farm in Yoknapatawpha County, a fictional rural county in Mississippi. They are incredibly poor, and the clan matriarch, Addie Bundren, is nearing death. Cash, the oldest son of the family, is a carpenter. As a last gift to his mother, he makes a coffin for her outside the window of the room where she lies dying. Anse, the family's stupid and weak patriarch, sends two sons, Darl and Jewel, on a lumber shipping job that will net the family a few extra dollars. Darl and Jewel set off, Darl knowing that it means he will not be present for his mother's death. Midtrip, they have an accident, and are forced to turn back; but Addie Bundren has already died.
Cash completes the coffin and they hold a funeral service. Darl and Jewel set off again. Dewey Dell, the only girl of the family, nurses her own secrets: she is pregnant, and will seek an abortion in town. Vardaman, the youngest child, is traumatized horribly by his mother's death, and continues to confuse her with the fish he caught and killed earlier that same day. Darl and Jewel return, and the family sets off to transport the body to Jefferson. It was Addie's longstanding wish to be buried among her birth family there.
Storms have made the journey difficult. The bridges are washed away, and after a night at Samson's farm the Bundrens end up having to backtrack to find a fordable part of the river. The stench is becoming more noticeable, and buzzards follow the wagon. The attempted crossing is disastrous: Cash's leg is broken, and he nearly drowns. The mules are killed. But Jewel manages to save the coffin from floating away downstream.
The Bundrens take shelter at Armstid's farm. To buy new mules, Anse sells Jewel's horse behind Jewel's back. The stench of the body is becoming stronger, and the family sets off in a hurry.
In Mottson, Dewey Dell tries unsuccessfully to find a druggist who will give her an abortion treatment. Meanwhile, the family has trouble with the sheriff, due to the horrifying stench of the body, and the Bundrens buy cement to make a cast for Cash's leg.
The Bundrens seek shelter at the Gillespie farm. No longer able to stand what is happening to the body, Darl sets fire to the barn in which the coffin is housed. Jewel manages to save the coffin, but the barn burns to the ground. Meanwhile, Cash's leg is clearly seriously injured, and the cement cast has only made matters worse.
The next day, they arrive in Jefferson and bury Addie. Because of arrangements made by his own family, Darl is captured and taken off to a mental institution in Jackson. Cash sees Peabody, the county doctor, who does the best he can for the damage leg. Dewey Dell is fooled by a shop assistant, and ends up trading sex for a bogus abortion treatment. Anse, his wife just recently buried, finds a new wife in town. As the Bundrens are setting off to return home, he brings the woman out and introduces her as his new bride.