Based on the Pulitzer Prize-winning novel by Booth Tarkington, The Magnificent Ambersons is set in a Midwestern American town that is fast becoming a sprawling city due to industrialization and the rise of the automobile. In the midst of this we meet the wealthy and socially prominent Amberson family. They will find that their influence fades in a new world as romantic entanglements that cross generations seal their fates as their fortunes change.

Act One: MAJOR AMBERSON sweeps into a sleepy Midwestern village and recreates it into a town with a central district formed around a neighborhood dominated by his own spectacular mansion and influence. His daughter ISABELLE is the catch of the county and seems to have caught the eye of a driven working class boy EUGENE MORGAN, but rejects him for the sensible WILBUR MINAFER. Wilbur's sister FANNY is distraught to see Eugene leave town to seek his fortune, he not knowing she secretly loves him. Many years pass and Isabelle and Wilbur have one son GEORGE, who as the sole heir to the Amberson fortune grows up with every privilege and advantage. His Aunt Fanny and his mother's brother UNCLE GEORGE look on as their nephew grows up spoiled and arrogant in a town where the name “Amberson” guarantees him power and social position. Eugene returns to the town after decades away, recently widowed and in the company of his lovely daughter LUCY, who immediately captures George's heart. Fanny is excited at Eugene's return and his prospects as the creator of a new “horseless carriage” but soon sees that the spark between Eugene and Isabelle is still there. This does not go unnoticed by George, who returns to college while continuing to romance Lucy. Months pass and many letters are exchanged as Eugene's factory begins to produce automobiles as he spends much of his time in the company of Isabelle, as a frustrated Fanny is included as a means to squelch gossip. Wilbur passes away and George returns from school with the expectation that Lucy will want to marry him; she refuses to commit until George chooses a career for himself. Satisfied with living the life of a gentleman, George allows his relationship with Lucy to fade as Eugene and Isabelle seem to be free to re-kindle their romance. An alarmed, jealous Fanny sets George upon an angry path when she tells him people are gossiping about his mother and Eugene which leads him to insult Eugene and formally break things off with Lucy. George whisks Isabelle off on an extended world tour to keep her away from Eugene as the sleepy town suddenly finds itself turning into a noisy, polluted city.

Act Two: Three years have passed and George and an ailing Isabelle return home to what is now an unfamiliar city where the name “Amberson” no longer carries prestige and Major Amberson's fortune is depleting rapidly. As Isabelle passes away, George will not allow Eugene anywhere near her. In rapid succession Major Amberson dies broken-down and penniless and Uncle George leaves the family to seek work elsewhere. George and Fanny find themselves with nothing but each other and leave the luxurious Amberson Mansion for a boarding house. As Fanny is financially destitute it is up to George to provide for her and he takes a dangerous job in order to secure a salary that will keep his aunt in a semblance of comfort. Eugene is now the wealthiest and most-powerful man in the city, and Lucy hopes there can be a reconciliation between him and George, and eventually between George and her; but an angry Eugene will not forgive him. As George wanders the lonely and now unfamiliar city at night, he is struck and seriously wounded by an automobile. Eugene is made to see that if he is to be true to his one true love Isabelle, he must be there for her son and extends his hand in friendship to George as the story ends.