The narrative begins with the discovery of a murder on a train, where a man named Francis Burnham is found dead in a first-class compartment. Medical professionals, including Thorndyke, determine that he was shot at close range, and evidence suggests that the murder was premeditated. Among the clues found are fragments of an electric bulb and a circular letter from the Women's Emancipation League, which raises suspicions about the involvement of suffragists. Miss Isabel Dalby, a member of the League, is arrested after a sheet of the same letter is found in her possession. Her alibi is weak, as she was seen boarding the same train, and circumstantial evidence mounts against her. Cadmus Bawley, a fellow League member, insists on her innocence and seeks Thorndyke's help for her defense. As the investigation unfolds, Thorndyke discovers that Burnham was carrying a large sum of money intended for a bank branch, which adds a potential motive for robbery. The inquest reveals conflicting testimonies, particularly regarding a handbag that Miss Dalby was seen carrying, which later goes missing. Thorndyke's investigation leads him to suspect that the letter found in the train compartment was planted to frame Miss Dalby. He deduces that the murder may have been committed in a tunnel where the sound of a gunshot would be masked by a passing express train. The presence of the letter suggests a deeper conspiracy involving the suffragist movement. As the case progresses, Thorndyke receives a telegram indicating a new lead, prompting him to travel to Folkestone. There, he uncovers a connection to a criminal gang, revealing that the murder was part of a larger scheme involving theft and deception. The gang had used the suffragist movement as a cover for their activities. The narrative culminates in a dramatic confrontation aboard a ship, where Thorndyke identifies the true murderer, who had attempted to frame Miss Dalby. The criminal's attempt to escape leads to a fatal accident, clearing Miss Dalby of all charges. The story concludes with the revelation of the intricate web of deceit and the clever deductions that led to the resolution of the case, showcasing Thorndyke's exceptional investigative skills.
By R. Austin Freeman · First published 1922 · Genre: Mystery, Crime, Detective Fiction