Plot
The film opens with a montage of the New York City borough of Manhattan, accompanied by the initial clarinet solo of George Gershwin's Rhapsody in Blue. The work continues as an overdubbed narrator recites a succession of ideas for Chapter One of a book about a man who loves New York City. The narrator is Isaac Davis, a twice-divorced 42-year-old television comedy writer. Isaac is dating Tracy, a 17-year-old high school student. Isaac's best friend is Yale Pollack, a college professor married to Emily. They are at Elaine's. As the friends walk home after the double date, Yale confides to Isaac he is having an affair with another woman. Isaac is intrigued, and keeps Yale's secret.
While Isaac and Tracy are visiting the Guggenheim Museum, they unexpectedly meet Yale, on a date with Mary Wilkie, the woman Yale mentioned to Isaac. Isaac is annoyed and offended by Mary's cultural snobbery and intellectual pretentiousness, and later tells Tracy he doesn't understand Yale's behavior. Several days later, Isaac meets Mary again at an Equal Rights Amendment fundraiser at the Museum of Modern Art. Mary and Isaac have coffee, and she invites him to walk her dog with her. They walk to a park under the Queensboro Bridge and talk until the lights on the bridge signal sunrise.
Despite his attraction to Mary, Isaac continues his relationship with Tracy, but emphasizes to her that it cannot be long-term. Tracy says she is in love with Isaac and has been accepted to an acting program in London. Isaac encourages her to take full advantage of the opportunity and dismisses her feelings for him, urging her to think of him and their relationship as "just an interesting detour on life's highway".
Yale breaks up with Mary, and suggests that Isaac date her. Isaac breaks up with Tracy, who is devastated when Isaac tells her he is in love with someone else. Mary and Isaac begin dating. Curious about Isaac's new girlfriend, Emily organizes a double date, unaware of the awkwardness. As the couples walk past a bookstore, Isaac sees a book by his ex-wife: Marriage, Divorce, and Selfhood. Emily reads passages from the book aloud, amusing Mary and Yale and humiliating Isaac.
Upon returning home, Mary tells Isaac she is still in love with Yale and wants to break up. Furious and hurt, Isaac walks to the college where Yale teaches and angrily confronts him. Isaac demands to know why Yale suggested he date Mary, and criticizes Yale's rationalizations for his extramarital affairs. Yale says he met Mary first and is in love with her, and excuses his behavior by saying he is only human. Later, Isaac talks with Emily about Yale's cheating and their breakup, and Emily reveals her pique at Isaac for introducing Mary to Yale.
Isaac lies on his sofa, dictating an idea for a short story. He muses about people in Manhattan who create unnecessary neurotic problems for themselves and then "certain things that make life worthwhile" for him, listing works of art, music, and literature, and then "Tracy's face". Isaac pauses and sets down the microphone. He peruses a gift Tracy had given him, a harmonica. Unable to reach her by phone, Isaac runs to her family's apartment building and sees she is about to depart for London. He approaches and tells Tracy he's changed his mind and doesn't want her to go because "I just don't want that thing I like about you to change". Tracy says the plans have been made and she has to go, but reassures Isaac, "not everybody gets corrupted...you have to have a little faith in people". Isaac smiles slightly. The film closes then with a montage of the Manhattan skyline shrouded in twilight and, as at the beginning, accompanied by Rhapsody in Blue.
