Thirteen guests gather for drinks at actor Charles Cartwright's seaside escape. Benign Reverend Babbington, who rarely imbibes, takes one sip of his beverage and keels over dead. Soon after Sir Bartholomew Strange convenes the same party and meets his own end after swallowing port. One death could be natural, but two mean murder. Hercule Poirot, who was present at both affairs, stages a third soirâ ee to catch the cocktail killer.