Just before midnight on New Year's Eve, 1946, Broadway actress Sheila Page shoots her husband Barney and then rushes to see her friend, William Williams. After a distressed Sheila confesses her deed to William, he suggests they talk to John Friday, Sheila's producer. As Sheila and William, an oddball poet, are walking up to John's apartment, Sheila wishes that she could relive the past year, insisting that if she had it to do over, she would not make the same mistakes twice. Upon reaching John's door, Sheila notices that William has disappeared and then gradually realizes that it is now New Year's Day, 1946. After telling a baffled John that she is not going to London, as previously planned, but will remain in New York, Sheila dashes home. Sheila is relieved to see the alcoholic Barney alive and sober and happily embraces him. Later, during their New Year's Day breakfast party, Sheila warns William to avoid a woman named Mrs. Eloise Shaw, as she will have him committed to an insane asylum. No sooner does Sheila issue this advice than William is introduced to Eloise, a vapid socialite who bankrolls struggling male artists. To Sheila's surprise, Paula Costello, the English playwright with whom Barney had an affair during the previous 1946, then crashes the party. Paula, who had previously met Barney in London while Sheila was performing in her play, Say Goodbye , begins a flirtation with Barney, but is rebuffed by the knowing Sheila. Angry at Sheila for chasing Paula away, the now- drunken Barney, a washed-up playwright whose early hit play made Sheila a star, leaves to find Paula. Later, Sheila confides to William that she knows that Barney will fall in love with Paula, begin to drink heavily and then grow to hate her. After vowing to William that she can change her own destiny, Sheila informs Barney that they are going to California. Twelve weeks later, Sheila and a sober Barney are enjoying themselves in Los Angeles when they receive an anonymous play from John. Barney is excited about the play, but as soon as Sheila learns that it is Say Goodbye , she rejects it. Barney and Sheila argue bitterly about the play, and Barney goes out to get drunk. John then arrives, anxious for Sheila to endorse the project, but Sheila refuses to consider doing it until John promises to keep Paula in London during the entire run. While the play is in try-outs in New Haven, however, Barney shows up with Paula. Barney insists that he asked Paula to come only to rewrite the second act and convinces Sheila that Paula is actually in love with John. During the play's successful Broadway run, however, Paula and Barney begin an affair and Barney returns to drinking. At John's Thanksgiving theater party, an intoxicated Barney openly insults Sheila and then kisses Paula on a balcony. When he is discovered by Sheila, Barney stumbles to the front of the balcony and falls over the railing. Later, Sheila is informed that, as a result of the fall, Barney has become paralyzed, but should be able to walk again if he gets complete rest and stops drinking. Still determined, Sheila leaves the play to nurse Barney, but Barney refuses to speak to her. Sheila then learns that William, who took up with Eloise, has been committed to an insane asylum. When she visits the dazed but philosophical William, he states that he now understands about the previous year. On Christmas Eve, after Sheila returns to the theater, Barney invites Paula over. Although Barney is anxious to resume the affair, Paula, having heard that he will not walk again, announces she is going back to London on New Year's Eve. When Sheila finds Paula with Barney, she demands that Paula take her husband to London, but Paula declares that the affair is over. On New Year's Eve, Sheila convinces John to stay with her until after midnight, but then discovers that Barney has left her for Paula. At the docks, Barney, who is now walking with a cane, surprises Paula in her stateroom, but she coldly rejects him. Just before midnight, a hate-filled Barney denounces Sheila for ruining his life and threatens her with his cane. As he is about to strike her, William, having escaped from the asylum, shoots and kills Barney. John then arrives with the police, and as William is taken into custody, he comments that while the details of destiny were changed, the results remained the same.