On October 29, 1929, several New York City society figures are reeling from the stock market crash. They converge at the home of James Stanton Emerson, John Boles, for a cocktail party, each reacting to the news in their own way. Emerson arrives late, now bankrupted, and slips away to his office, intending to end his life. As he writes a goodbye note, a letter waiting for him is opened—it is from Mary Lane, Margaret Sullavan, a woman from his past he has long forgotten.
Reverting to the last year of World War I, James, an officer stationed near Mary Lane, is introduced to her at a formal party. She has orchestrated a chance encounter and reveals she has long harbored affection for him. They spend the night together, and it is implied they become intimate.
Months later, James’s unit is sent to France. Mary learns she is pregnant, and her family arranges for her to go to New York to recover with her broadminded aunt Julia Warren, Billie Burke. When her child is born, the Armistice is declared, and James returns but does not remember Mary; he is swept into his social circle of wealth and privilege. Mary, heartbroken, decides to raise their son, Jimmy Jr., alone while keeping wary of his returns and knowing he has married someone else.
A decade passes. Mary has become a successful shop owner, living a life shaped by independence and the memory of her past. Jimmy Jr. is now about 10 and in military school. During a holiday visit, Mary’s suitor, a man named Dave Reynolds, appears—he has proposed several times, but she has refused. The family heads out to a club for the New Year’s Eve ball drop; Mary promises to call Jimmy after midnight to tell him whether Dave has proposed and whether she has accepted.
At the club, Mary runs into James again—this time, both notice the familiar spark but James does not remember their earlier history. They share a quiet, charged moment, and she agrees to go home with him. They spend the night together, and she keeps their past concealed, telling him it is best to remain strangers. Back home, Jimmy, who has spent the night worried, learns that Mary is not pursuing a proposal: his declaration is that he wanted her to have a father, not just a partner.
On October 28, 1929, Mary lies on her deathbed with heart trouble and writes a long letter to James that recounts the life she has led since their first night together and asks him to be a parent to their son after her departure. Jimmy is summoned from his school and learns of his mother’s death; Aunt Julia delivers the letter to James’s home.
Back in the present, James finishes reading the letter, puts away his gun, and discards his suicide note. His wife confronts him about their loveless marriage, and he reveals that he has found something to live for, blessing her pursuit of happiness with her other partner. He goes to Aunt Julia’s apartment, where Jimmy opens the door in tears. James embraces his son and, in a decisive moment, reveals that he is the father—an emotional turn that marks a bold shift from the original Zweig story.
