Eccentric and wealthy New York widow Ursula Pell loves playing cruel jokes on her guests and particularly on her niece and nephew who are destined to inherit the millions in gems left to her by her late husband. Therefore when she is found brutally murdered in a locked room the morning after a dinner party her niece Iris the most recent victim of Ursula's humiliating pranks is first suspected until all the clues point to her nephew. Where did she stash the gemstones and the much mentioned diamond pin promised Iris. Enter Fleming Stone, famous detective who hopefully can prove the innocence of the nephew, the true value of the diamond pin and discover WHO killed Mrs. Pell. - Summary by Celine Major