The Murder on the Links

The narrator, Captain Arthur Hastings, is returning to London from Paris when he meets a spirited young American actress who calls herself "Cinderella." The next morning, Hastings's friend, the Belgian detective Hercule Poirot, receives an urgent letter from Paul Renauld of the Villa Geneviève in Merlinville, France. Renauld claims his life is in danger due to a secret and begs Poirot to come immediately. Poirot and Hastings travel to France, but upon arriving at the villa, a policeman informs them that Renauld was murdered that morning.

Poirot and Hastings meet the examining magistrate, M. Hautet, and the Commissary of Police, M. Bex. They learn that Renauld’s body was found stabbed in the back, lying in a freshly dug grave on an adjacent, unfinished golf course. His wife, Eloise Renauld, was discovered bound and gagged in her bedroom. The servants give conflicting testimonies. Françoise, the housekeeper, insists she saw a neighbor, Madame Daubreuil, visiting Renauld the previous night. A younger maid, Denise, claims the visitor was an unknown, English-speaking woman. In the dead man’s overcoat pocket, the police find a threatening love letter signed "Bella." In Renauld's study, Poirot finds a fragment of a torn cheque made out to "Duveen" and a long, black woman's hair on an armchair. The murder weapon, a distinctive paper knife, was left in the wound.

Mrs. Renauld recounts her version of events. She claims two masked men entered her bedroom around 2 a.m., bound her, and abducted her husband while demanding "the secret." She identifies the murder weapon as a gift from her son, Jack. She also reveals that her husband had sent Jack to South America on business via a ship from Cherbourg. A smashed wristwatch is found showing seven o'clock; Poirot deduces it was set to 2 a.m. and smashed, but because it continued running, it revealed the attempt to create a false timeline. When Mrs. Renauld formally identifies the body, she faints. Poirot confirms her bonds and swoon were genuine. At the crime scene, they meet the arrogant Parisian detective M. Giraud, who focuses on physical evidence. Poirot, however, is intrigued by a piece of lead piping near the grave and notices that a flower bed beneath Mrs. Renauld's window has been smoothed over, erasing any footprints.

The investigation turns to Madame Daubreuil, who lives with her beautiful daughter, Marthe, in the neighboring Villa Marguerite. Madame Daubreuil denies any affair with Renauld. Afterwards, Marthe secretly approaches Poirot, anxiously asking if anyone is suspected. Poirot tells her the suspects are two Chileans. He then reveals to Hastings that he recognizes Madame Daubreuil from an old murder case. Suddenly, Jack Renauld appears, explaining his ship was delayed. He admits to quarreling with his father over his forbidden love for Marthe. Shortly after, the murder weapon is discovered stolen from the shed where the body was kept. Hastings confesses he had taken "Cinderella" to see the body and left the shed unlocked, providing an opportunity for the theft.

The following morning, a second body is found in the same shed. The victim is an unknown man, stabbed with the stolen dagger. The doctor determines the man has been dead for at least forty-eight hours, a timeline that seems impossible since the dagger was only stolen the previous day. Hastings learns from a station porter that Jack Renauld arrived in Merlinville on the night of the murder, a fact Jack concealed. Poirot returns from a quick trip to Paris and reveals his own deductions, stating the second victim died of an epileptic fit and was stabbed post-mortem. He then shows Hastings a newspaper clipping identifying Madame Daubreuil as Jeanne Beroldy, a woman acquitted of her husband's murder twenty years earlier in a case involving a story of masked men and a "secret" that echoes Mrs. Renauld's testimony. Her lover, Georges Conneau, confessed to that crime and disappeared. Poirot concludes that Paul Renauld was, in fact, Georges Conneau. Blackmailed by Madame Daubreuil, Renauld planned to fake his own death using the body of a tramp who had died of a fit in his garden, with his wife acting as his accomplice.

Giraud arrests Jack Renauld, believing the quarrel over Marthe was the motive and that Mrs. Renauld lied to protect her son. Upon seeing her son arrested, Mrs. Renauld faints and falls unconscious from the shock and a resulting head injury. Poirot reveals to Hastings that the "Bella" letter was for Jack, who had accidentally taken his father's overcoat, leaving his own behind. Poirot then shows Hastings a photograph of Bella Duveen, and Hastings recognizes her as "Cinderella." They travel to England and find her performing with her twin sister. The girl Hastings met is Dulcie Duveen. Believing her sister Bella is the killer, Dulcie allows Hastings to mistake her for Bella and confirms his incorrect theory about the murder, admitting she stole the dagger to protect her sister. Hastings, now in love with Dulcie, lies to Poirot and provides her with a false alibi.

Back in France, Jack refuses to defend himself, believing Bella is the murderer. Just as he is about to be committed for trial, Bella Duveen appears and confesses to save him. It is revealed that Jack and Bella arrived at the crime scene at the same time, and each assumed the other was the killer. Poirot exposes the true murderer: Marthe Daubreuil. She had overheard Renauld’s plan to fake his death and saw an opportunity to marry a wealthy Jack. She used a third, identical dagger, a gift from Jack, to kill Renauld as he was digging the grave. To force Marthe's hand, Poirot arranges for the now-conscious Mrs. Renauld to publicly disinherit her son. Marthe then attempts to murder Mrs. Renauld but is stopped by Dulcie, a trained acrobat, whom Poirot brought as part of his trap. Marthe dies in the struggle. Madame Daubreuil disappears. Jack and Bella, their love affirmed through their mutual sacrifices, plan a new life in South America, while Hastings and Dulcie become a couple.