Chief Inspector Japp, afraid that he will soon find himself unemployed, needs Poirot's assistance in solving a string of jewel robberies. Japp is under intense pressure to catch the thief but Poirot counsels patience. When the jewel thief strikes again, Poirot and Captain Hastings go to the home of Marcus Hardman, a jewelry collector from whom an emerald necklace was stolen. Poirot is apparently quite taken with the exiled Russian Countess Vera Rossakoff and to Japp's great consternation, days pass with no progress in the case. With the famous detective otherwise occupied, Hastings and Miss Lemon decide to investigate on their own. Poirot however knows well who the criminal is.