Scott Henderson, Alan Curtis, a 32-year-old engineer, starts the night in Manhattan after a brittle quarrel with his wife on their anniversary. He picks up a troubled woman at Anselmo's Bar and, drawn to the anonymity of the evening, they ride to a nearby stage show together. The show’s star, Estela Monteiro, Aurora Miranda, grows furious when she realizes she and the mystery woman share the same distinctive hat, a tension that hints at a deeper mystery lurking behind the curtain of their volatile lives. When Henderson returns home, he is met by Police Inspector Burgess, Thomas Gomez, and two officers who question him because his wife has been strangled with one of his neckties. Although Henderson has a solid alibi, the bartender, a taxi driver, and Monteiro remember him, yet all deny seeing the phantom lady. The case unfolds with a chilling sense of doubt, and Henderson cannot even clearly describe the woman who could seal his fate. He is tried, convicted, and sentenced to death, leaving his fate—and his innocence—hanging in the balance.
Carol Richman, known as "Kansas," Ella Raines, Henderson's loyal secretary who harbors a quiet love for him, refuses to accept the verdict. She resolves to prove his innocence and begins with the bartender, spending long nights at the bar and quietly unnerving him. Her pursuit takes a bold turn when she follows Henderson home, and a tense street confrontation nearly ends in tragedy as bystanders intervene and Henderson is nearly run down in traffic. Burgess, glimpsing a glimmer of doubt, offers to help Kansas unofficially and shares new details, including fresh information about the show’s drummer, Cliff Milburn, Elisha Cook Jr., who had tried to catch the phantom lady’s eye.
Kansas clothes herself for a new line of inquiry, dressing provocatively to attract Cliff’s attention during a performance. As she flirts and draws him in, they meet afterward, venture to an underground jam-session, and retreat to his apartment. In a moment of bravado, Cliff brags that he was paid $500 for his false testimony. A spilled purse reveals a paper with Cliff’s particulars, and he accuses Kansas of deceiving him. She escapes, leaving the purse behind, and a new danger emerges when an unidentified man arrives later to confront Cliff, accusing him of lying about the bribe to deny the phantom lady’s existence—an accusation that ends with Cliff’s brutal murder.
Jack Marlow, Henderson’s best friend who has just returned from South America, reenters the story, ostensibly to assist Kansas in saving Henderson. In truth, he nurtures a deteriorating mental state and covertly works to undermine Kansas’s efforts, adding another layer of complexity and danger to the pursuit of truth. With Burgess temporarily away on another case, Kansas and Marlow press forward, tracing Monteiro’s hatmaker, Kettisha, until one of the milliner’s clients—Ann Terry, Fay Helm—emerges. They discover Ann under a doctor’s care, having collapsed months earlier when the man she was to marry died suddenly, a tragedy that left her emotionally unsettled. Although Kansas cannot extract information from Ann directly, she does recover the hat, a crucial clue in the case. Marlow proposes that they wait for Burgess at his apartment, but time is running out.
The investigation leads to a pivotal moment of truth: a missing purse, hidden papers with Cliff’s details, and a confession that reveals complicated feelings and tangled motives. Marlow’s confession about his own jealousy—how he was driven to anger when Henderson’s wife wouldn’t run away with him, an artist—peels back another layer of the case, showing how desire, rage, and fear can blur the lines between innocence and guilt. Burgess arrives just in time to confront the tangled truth, and Marlow’s own actions culminate in a fatal fall from a window, an act that resolves the mystery in a way that frees Henderson and clears the path for a future with Kansas, offering a glimmer of hope amid the tragedy.
