A criminal lawyer's wife faces blackmail when she has an affair.

Although she loves her husband, prominent defense attorney John Prentice, and is confident that he loves her, Evelyn Prentice bemoans his long working hours. While John is preoccupied with acquitting the seductive Mrs. Nancy Harrison, a socialite on trial for manslaughter, Evelyn is approached in a nightclub by gigolo Lawrence Kennard. Later, after John finds himself on the same Boston-bound train as Nancy, Evelyn receives a book of Kennard's poetry and an invitation to tea. At the urging of her best friend, Amy Drexel, Evelyn accepts Kennard's invitation but maintains her loyalty to her husband. Soon after John returns from Boston, Evelyn receives a package containing a woman's watch, which has been inscribed "To Nancy, from John," and a note from the train company explaining that the watch was found in John's drawing room. Devastated, Evelyn has another rendezvous with Kennard but, before she has compromised herself, tells him that their flirtation is over. Amy, meanwhile, shows Nancy's watch to John, who tells her that Nancy planted it in his room to destroy his marriage. Although neither John nor Evelyn discuss the watch, they both agree to take a long trip to Europe with their daughter Dorothy. Before they leave, however, Kennard telephones Evelyn and demands that she come to his apartment. There, Kennard shows Evelyn three letters that she had written to him and insists on $15,000 in blackmail payment. In spite of the relative innocence of the letters, Evelyn panics and grabs a gun from an open desk drawer. At that moment, Judith Wilson, Kennard's abused girl friend, enters the apartment's back door and hears a gunshot in the next room. Before Judith sees her, Evelyn rushes out the front door and returns home, determined to reveal nothing to John. However, when she learns that Judith has been accused of killing Kennard, Evelyn convinces John to forego their trip to Europe and defend Judith. From Judith, John learns first that Kennard was seeing the "wife of a prominent man" and then later that he had kept a diary. While John's investigator tracks down the diary, Evelyn grows more and more uneasy about Judith's chances of acquittal. Then on the last day of the trial, Evelyn decides to tell the truth and goes with Amy to the court. During the district attorney's summation, John receives Kennard's diary, in which Evelyn is identified as "the prominent wife." At the same time, Evelyn, unable to endure the prosecutor's attack on Judith, interrupts the proceedings and demands to be heard. Although John tries to block her testimony, Evelyn confesses that, during a struggle with Kennard, the gun went off accidentally, apparently hitting Kennard. To the surprise of the court, John questions Judith and, using Evelyn's testimony against her, forces her to admit that she had shot Kennard after Evelyn had left. John convinces the jury that Judith killed Kennard in self-defense, and then informs Evelyn that all is forgiven and forgotten.