While traveling by train, Elspeth McGillicuddy witnesses a brutal murder through the window of a passing carriage, setting off a desperate search for a body that has vanished without a trace. When the authorities dismiss her account due to a lack of physical evidence, she turns to her friend, Miss Jane Marple, to investigate the impossible crime. Marple must navigate a web of deception within a wealthy, dysfunctional family to uncover the truth. The narrative utilizes a classic third-person perspective, focusing on the methodical observation and psychological insight that define Marple's investigative process.

This novel remains a staple of the golden age of detective fiction, frequently cited for its clever subversion of the witness-testimony trope. Readers often highlight the charm of Miss Marple’s unassuming nature, which allows her to extract information from suspects who underestimate her intellect. The pacing is widely regarded as steady and deliberate, characteristic of Christie's ability to construct intricate puzzles within confined social circles. The resolution is frequently noted for its logical consistency, satisfying those who enjoy piecing together clues alongside the protagonist.