In Agatha Christieâs short story, âThe Adventure of the Western Star,â Poirot investigates the case of a missing diamond, âThe Star of the Eastâ, 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.