Plot
In the 1870s, New York City is dominated by a community of old-money families whose lives are guided by strict codes of conduct. The elite police their own through ostracism or worse.
Gentleman lawyer Newland Archer is planning a society marriage to May Welland. May's cousin, Countess Ellen Olenska, returns to New York City after a disastrous marriage to a Polish count. When he was unfaithful to her, she left him with the assistance of his secretary, Monsieur Riviere, with whom she was rumored to have lived for the following year.
Due to high society's rigid standards, Ellen's conduct is considered particularly scandalous, so she is initially ostracized. Archer is indignant at the unfair treatment and helps Ellen's family restore her place in the community. He does so by convincing the van der Luydens, the leading New York family, to host a dinner for her.
Ellen meets financier Julius Beaufort, who entered New York society by marrying into the Townsend family. His status ensures he is treated courteously, but his philandering makes him widely disliked. Julius begins flirting with Ellen but meets his (social) end when the New York elite — sick of his indiscretions — refuses to bail him out during a financial panic.
Archer asks May to marry him. Although she senses he is not ready, she accepts. May's intuition proves to be correct. Archer is drawn to Ellen's unconventional views on New York society, which contrast with May's seeming passivity, lack of personality, and fondness for idle leisure.
Ellen attempts to divorce the count, who retaliates by threatening to publicize her supposed adultery. As such an accusation would humiliate the entire Welland family, the community urges Archer to intercede. He sympathizes with Ellen but does his duty and pressures her to call off the divorce.
Realizing that he has fallen in love with Ellen, Archer tries to resolve the issue by urging May to rush into the wedding. Suspicious, May asks him once again if his love is genuine. Archer reassures her that it is.
Nonetheless, Archer cannot help confessing his love to Ellen. Although she loves him back, she declines his advances. Ellen bitterly explains that she was ready to endure the scandal of a divorce but Archer and May were not. To avoid further temptation, she moves to Washington.
May advances the wedding date, and it goes off without a hitch; Ellen declines her invitation. Archer's marriage is comfortable but boring. He eventually arranges to meet Ellen in secret. They admit they still love each other.
The count offers Ellen money and even some personal freedom to return to him. Ellen's family pressures her to take the deal by cutting her personal allowance. However, Ellen declines the offer. Archer and she continue meeting in secret, but Archer's elaborate deceptions arouse May's suspicions. Archer and Ellen decide to make love one time; but before they can do so, Ellen abruptly announces that she is returning to Europe, aided by a generous allowance from her grandmother, Mrs. Mingott.
May throws a lavish farewell party for Ellen. Afterward, May tells Archer that she is pregnant. She admits that she shared the news with Ellen before confirming the pregnancy. Archer realizes that he has gravely underestimated May, who suspected his unconsummated love affair all along. He also realizes that Ellen left America because she could not bring herself to have an affair with a married father and that the entire community has been working behind the scenes to separate him from Ellen, while believing that they already had consummated their love.
A quarter-century passes, during which Archer and May raise three children. May dies of pneumonia, leaving him a widower. Ironically, high society's unwritten rules have faded away, and Archer's son Ted is engaged to the daughter of Beaufort's mistress, who became his second wife.
Ted invites Archer to a father-son holiday in Paris. He reveals that he planned the trip so that Archer could meet Ellen again. Ted says that on her deathbed, May confessed to him that "when she asked you to, you gave up the thing you wanted most." Archer replies, "She never asked me."
Walking to Ellen's apartment together, Archer cannot bring himself to visit her, so sends Ted in his place. He reflects on their time together but also what his wife had done and then walks away.