Major Amberson creates the family fortune in the 1870’s. When Isabel, his daughter, is about twenty years old, she is courted by two men: Wilbur Minafer, a quiet businessman, and Eugene Morgan, a debt-ridden lawyer. Morgan destroys his chances in a drinking incident on the Amberson estate. Isabel marries Wilbur, and their only child is George Amberson Minafer. Isabel spoils her wild boy. George treats others with contempt and was once expelled from a prep school for his bad behavior. The townspeople hope to see George get his comeuppance.

When George is an eighteen-year-old college student, a ball is held in his honor at the Amberson mansion. Here George meets Eugene Morgan, his mother’s former suitor, and falls in love with his nineteen-year-old daughter, Lucy. Eugene had left town at the time Isabel dismissed him, become an inventor, and returned to town twenty years later to manufacture horseless carriages.

George informs Lucy that he has no career plans. During their sleigh ride the next day, George attempts to embarrass the inventor by racing his sleigh past Morgan’s inoperative horseless carriage. George’s sleigh crashes, and he and Lucy have to hitch a ride back into town on the new vehicle. After George returns home for summer vacation, he renews his relationship with Lucy. When she and her father attend one of the Major’s weekly Sunday dinners, the latter reveals that Isabel and Eugene had once been engaged. On the night before George returns to college, Isabel tells him of Wilbur’s declining health. His father is deeply worried because he and George’s uncle, George Amberson, have tied up much of the family’s assets in a company owned by their friends, an investment that is turning sour.

During the following summer, George proposes to Lucy when he hears a false rumor that she is engaged to Fred Kinney. Though she declines to say either yes or no at that time, she promises to settle the matter before he returns to school. On George’s final night before returning to college, Lucy still leaves their relationship unsettled. She tells him that they are “almost” engaged. While back at college, Isabel writes George that she has gotten the ailing Wilbur to take a vacation and that his uncle, Sydney Amberson, and his wife have taken their one-third share of the Amberson fortune. Then Wilbur dies, and his business failure leaves Uncle George and Fanny broke. George Minafer gives his father’s insurance money to Fanny as compensation.

After George’s graduation from college, he is horrified to see five new houses on the family estate—the Major’s attempt to recoup the family fortune. George becomes increasingly hostile to both Eugene Morgan and his automobiles. Lucy refuses to go beyond their “almost” engagement because George, unlike her father, refuses to pursue a career. George then insults Eugene Morgan during a Sunday dinner. Angered by his differences with Lucy and by a rumor that Isabel had always been in love with Eugene, George confronts the rumormonger, Mrs. Johnson, and then bars the industrialist from his house. George then tells Isabel that he has to protect the Amberson name from scandal, and bullies her into ceasing all contact with Eugene Morgan. George subsequently tells Lucy that he and Isabel are to leave the country indefinitely.

Then the Amberson holdings fall into decay, the Major’s new houses prove a failure, and Uncle George and Fanny invest heavily in an ill-fated headlight invention. Against Uncle George’s advice, Fanny secretly stakes all of her money on the scheme. After several years abroad, George brings his mother back when she is gravely ill. As she lay...