In the short story The Double Clue, Marcus Hardman is a wealthy collector. After one of the tea parties which he regularly hosts, a valuable emerald necklace which once belonged to Catherine de Medici was stolen. He was reluctant to call in the police because of the high society guests involved and so he asked Poirot to help.
Hastings describes Hardman as "a small man, delicately plump, with exquisitely manicured hands and a plaintive tenor voice... somewhat of a celebritiy and the fashionable life was his profession."
During his interview with Poirot he constantly emphasised discretion and the avoidance of publicity. He wanted no scandal, just the return of his stolen jewels. Hastings found him "writhing in an agony of indecision."
Portrayals[]
Marcus Hardman is played by David Lyon in the film adaptation of The Double Clue in Series 3 of ITV's Agatha Christie's Poirot. The portrayal is close to that in the original story except that he does call in the police after the theft.