In 1870s New York City, gentleman lawyer Newland Archer is planning to marry the respectable young May Welland. May's cousin, the American heiress Countess Ellen Olenska, has returned to New York after a disastrous marriage to a dissolute Polish Count. At first she is ostracized by society and vicious rumors are spread, but, as May's family boldly stands by the Countess, she is gradually accepted by the very finest of New York's old families. Archer prematurely announces his engagement to May, but as he comes to know the Countess, he begins to appreciate her unconventional views on New York society and he becomes increasingly disillusioned with his new fiancée May and her innocence, lack of personal opinion, and sense of self.