Lady on a Train

On her train to New York City, Nicki glances up from a mystery novel and witnesses a murder in a nearby building. The sight occurs before the train reaches Grand Central Station, leaving her shaken and convinced something foul has happened. When she reaches the city, she tries to report it, but the desk sergeant dismisses her as imagining things.

After arriving, she goes to the police but is dismissed because the murder appears to be only a report she saw in a novel. Determined to solve the mystery, she decides that Wayne Morgan must be able to unravel it, and she sets out to find him. She begins pestering Morgan to get involved.

Following Morgan and his fiancée into a theater, she sees a newsreel about the death of Josiah Waring that looks like an accident. She instantly recognizes the deceased as the murder victim from the earlier sighting. Her discovery pushes her to urge the detective to investigate further.

Nicki sneaks onto the grounds of Waring's mansion and is mistaken for Margo Martin, who was expected but has not arrived. During the will reading, the lawyer explains that Waring leaves most of his estate to Margo Martin, while others receive only token sums. Nicki snoops around and steals a pair of bloody slippers that contradict the accident story.

Two conspirators, Saunders and the chauffeur Danny, try to stop Nicki as she leaves the mansion with the bloody slippers. Her theft undermines the tale of an accident and suggests that a planned murder is at hand. The plot begins to tighten as the evidence points away from accident and toward foul play.

Back at Haskell’s, Nicki phones Morgan and pretends that a man is attacking her, hoping to draw him in. Unaware that Danny is present, she inadvertently triggers real danger as the threat closes in. She then makes another call to her father to seek help from him.

The group converges at the nightclub where Nicki confronts Margo and locks her in a closet. Nicki then steps on stage to sing in Margo's place, while the freed Margo reveals she was never part of the plot and exits. Soon after, Margo is murdered, escalating the danger around Nicki.

Arnold and Jonathan woo Nicki while Saunders has her called backstage. He and Danny admit their involvement and threaten her, but Morgan breaks into the room and Nicki takes the slippers back. A backstage fight ensues and Nicki returns to the stage to sing again, while Morgan warns that one of the people she is sitting with must be the killer.

Danny shoots Saunders as chaos erupts around the club. Nicki and Morgan leave with the slippers, but are arrested in the morning based on Danny's false information. Nicki tries to present the slippers, only to learn that Morgan's valet has them and reveals how clean they are after they have been cleaned.

Arnold, Jonathan, and Haskell arrive at the jail to pay Nicki's bail. Arnold admits that he had motive, but so did Jonathan and Wiggam and Saunders. They drive Nicki to the Warings offices, but nobody is there, and the uneasy ride ends with Nicki realizing danger still surrounds her.

Finding Jonathan in the building, Nicki accuses him and tells him that Arnold is the murderer. They hide in a room that matches the train sighting of the crime. Jonathan is revealed as the killer and boasts that he will kill Nicki and frame Arnold. Arnold arrives and a tense struggle follows as Morgan arrives and misreads the situation before the police finally arrive.

Nicki and Wayne Morgan are newlyweds on a train, enjoying their life after the case. She reads his newest book with gusto and asks the porter to delay making up their beds until she finishes reading. Morgan breaks the tension by telling her how the ending of the book goes, providing a light and playful close to the mystery.