Newland Archer watches the opera and notices his fiancée May Welland — and her disgraced cousin Ellen Olenska — seated in the Mingott box, setting Old New York society buzzing.

The opera evening continues. Newland and May's engagement is celebrated by their families. Newland is introduced to Ellen Olenska and immediately registers her as different from every woman he knows.

Old New York society debates Ellen Olenska's social standing. The Welland family asks Newland, as the future son-in-law, to help Ellen — and Newland's law firm is retained to advise her on a possible divorce from Count Olenski.

The van der Luydens — the final arbiters of Old New York's social acceptance — host a dinner that includes Ellen Olenska, effectively ratifying her social position. Newland feels the power of the tribe.

Newland visits Ellen at her rented house and finds a world entirely unlike his own — bohemian, European, honest. He is disturbed and enchanted. They discuss her marriage and her desire for freedom.

Newland formally advises Ellen against seeking a divorce from Count Olenski, arguing that New York society would not accept a divorced woman. He increasingly questions his own advice even as he gives it.

Newland escorts Ellen to her grandmother's house and to Beaufort's party. He sees how society simultaneously courts and condemns her. His attraction deepens as he watches Old New York's elaborate dance around her presence.

Newland begins to see May and their planned life together differently after his exposure to Ellen. He rushes the engagement, wanting to fix his future before his perspective shifts further.

Ellen confides more of her unhappy marriage to Newland. Their intimacy deepens. Newland begins to understand the full dimensions of what she escaped — and what returning to New York has cost her.

Newland encounters Ellen unexpectedly at the Metropolitan Museum. Their conversation, surrounded by art and without social chaperones, is the closest they come to a declaration.

Final preparations for Newland and May's wedding. Newland goes through the motions correctly while his interior life increasingly escapes the ritual's grasp.

Newland and May marry. The ceremony is described with precision and social detail. Newland experiences a moment of pure clarity — and suppresses it completely.

Newland and May honeymoon in Europe. Newland finds himself disappointed by the European cities he has long dreamed of visiting — or rather, discovers that what he wanted from Europe was not aesthetic experience but something he could not name.

The Archers return to their New York house. Newland discovers Ellen has moved from fashionable society to a marginal apartment in a bohemian neighborhood. Their first meeting after the wedding changes everything.

Newland and May settle into married life. Newland finds the settled life comfortable and increasingly airless. He tries to share his growing disquiet with May and discovers that she cannot receive it — not because she is stupid, but because her world has given her no framework for it.

The van der Luydens invite Ellen to their Hudson Valley estate, Skuytercliff. Newland joins the party and manages a private hour with Ellen. She tells him she cannot stay in America.

Count Olenski's agent approaches Ellen offering better terms for a reconciliation. Newland is consulted. He advises against it — then discovers he has advised incorrectly, for reasons he cannot fully name.

Newland tries to articulate to himself what he actually wants from his life — from Ellen — from the future. He fails to think it through to its conclusion because every path leads through a door Old New York will not open.

Newland and Ellen share a carriage ride that contains the novel's most extended physical intimacy — a moment held deliberately short of declaration. Newland returns home to May, who is planning a dinner party.

Society retreats to Newport for the summer. Newland watches Ellen navigate the rituals of resort life and realizes that Old New York has decided to manage her rather than exclude her — and that this management is its own form of exile.

Newland travels to Boston, ostensibly on business, intending to see Ellen and tell her something definitive. Ellen meets him with a letter from May — announcing her pregnancy. Ellen will leave for Paris.

The Archers host a farewell dinner for Ellen before her departure for Paris. Newland suddenly realizes — in a moment of collective observation — that everyone at the table has known all along. Old New York is not innocent; it is collectively protecting itself.

After the dinner, Newland confronts May about the pregnancy announcement — specifically its timing. May's responses reveal that she understood more than he imagined. The last illusion dissolves.

Epilogue, 1905. Newland Archer, a widower, is in Paris with his son Dallas. They are to visit Ellen Olenska. Newland reaches her door and turns back, unable to enter. He walks away and the novel ends.