Nicki Collins, a San Francisco debutante, travels to New York to visit her Aunt Aunt Charlotte Waring, with a plan to be met by her father’s employee, [Haskell](/actor/edward Everett Horton), who will help her settle in. The journey takes an unexpected turn when, just before reaching Grand Central, she glances up from a paperback—an intrigue penned by the novelist Wayne Morgan—and witnesses a murder unfolding in a nearby building. The moment shatters her calm, and the mystery she’s reading seems to have crossed into real life.
Upon disembarking, Nicki swiftly seeks help at the police desk, but the desk sergeant—Desk Sgt. Brennan—misreads her account, chalking the whole affair up to a vivid imagination sparked by the book in her hands. Undeterred, she becomes convinced that Wayne Morgan can solve the crime, and she tracks him down to press him into service. Her persistence pays off, and she and Wayne slip together into a theater to observe the aftermath of the case, where a newsreel reveals the seemingly accidental death of shipping magnate Josiah Waring. Nicki recognizes the victim, and the mystery deepens: this is no mere accident.
Unable to locate a precise crime scene, Nicki slips onto the grounds of Waring’s grand mansion. There she is mistaken for Margo Martin, the nightclub singer and supposed fiancée who never showed for the reading of the will. The legal proceedings begin, and Waring’s lawyer, Wiggam, declares the terms: a token $1 bequest to the nephews Arnold Waring and Jonathan Waring, while the bulk of the estate goes to Margo Martin. Nicki’s curiosity prompts her to snoop further, and she filches a pair of bloody slippers that contradict the accident story and hint at foul play. Two conspirators—Saunders, the nightclub’s manager and one of the heirs, and the chauffeur, Danny—do what they can to thwart her, but Nicki remains one step ahead.
Back with Haskell, Nicki makes another bold attempt to involve Wayne, phone-calling him and feigning that a man is attacking her, not realizing that Danny is already in the room and prepared to strike. A second call to her father interrupts the immediate danger, but when Nicki sings to him, Danny seizes the moment to move, snagging the slippers and attacking both Haskell and Morgan. Nicki afterward chalks up the sequence to a case of mistaken identity, yet the danger isn’t over.
The action shifts to the nightclub, and Nicki confronts Margo Martin, growing suspicious of the other woman. She locks Margo in a closet, then goes on stage in her place and sings to buy time. When Margo is finally freed, she reveals that she never cared for the plot and exits, only to be murdered soon after. The intrigue thickens as Arnold and Jonathan both court Nicki, while Saunders has her summoned backstage. He and Danny admit their involvement in the murder plot and threaten her, but Wayne bursts in, and Nicki retrieves the slippers once more. A flurry of backstage brawls erupts, Nicki escapes, and she returns to the stage to perform again.
Morgan learns that one of the people Nicki is seated with—Arnold, Jonathan, or Wiggam—must be the killer, and he races to warn her. Meanwhile, Morgan’s fiancée, convinced that he is two-timing Nicki, ends their engagement, adding personal stakes to the peril. Danny shoots Saunders, and Nicki and Morgan depart with the slippers, only to be hauled away at dawn on mistaken grounds, spurred by Danny’s misdirection. The slippers are finally recovered by Morgan’s valet, who reveals their remarkable cleaning and the truth behind the evidence.
Arnold, Jonathan, and Haskell show up at the jail to post Nicki’s bail, and Arnold contends that the Warings would like to meet her. He drives her to their offices, but there is no one there to greet them. They discuss the case, and Arnold acknowledges that both he and Jonathan—along with Wiggam and, notably, Saunders—had motives. Terrified, Nicki slips away from him and presses on.
In a tense confrontation, Nicki encounters Jonathan in a secluded room—the very room that matches the train-view crime scene—and she accuses him of being the killer. Jonathan confesses, bragging that his next step would be to kill Nicki, frame Arnold, and then kill Arnold again “to defend” Nicki. Arnold suddenly appears and wrests Jonathan’s gun, but Morgan arrives, misreads the situation, and Jonathan seizes control once more; the police arrive just as truth comes to light.
The film closes on a lighter note, with Nicki and Wayne Morgan as newlyweds aboard a train. She is so engrossed in his latest book that she orders the porter to let her finish reading before they settle in, and Wayne himself reveals that he will finish the story for her—ending their tale with a sly hint of what lies ahead.
