The collector Mr Shaitana invites four investigators and four people he privately believes have committed undetected murders to dinner. During an evening of bridge, Shaitana is stabbed while sitting apart from the tables, leaving every member of the suspected group with an opportunity.
Poirot, Superintendent Battle, Ariadne Oliver and Colonel Race divide the inquiry according to their different methods. Because the physical action is limited, Poirot treats bridge scores, memory and character as evidence, asking which guest possessed both the temperament to kill and the confidence to act within a room full of observers.