The Adventure of The Western Star

In Agatha Christie's short story, "The Adventure of "The Western Star," Poirot investigates the case of a missing diamond, "The Star of the East", belonging to Lady Yardly. But what is the connection between it and a similar diamond owned by the famous American film actress Mary Marvell? And why does a Chinese man want it returned? This short story originally appeared in the April 11, 1923 issue of The Sketch magazine.