Poirot investigates a series of murders, the first of which had all of the earmarks of a natural death. At a small dinner party at the home of a famous actor Sir Charles Cartwright, the local minister, Rev. Babbington drops dead after taking a sip of his pre-dinner cocktail. There is no evidence of poison either in the body or the glass and the coroner rules the death to be from natural causes. One month later at the home of Sir Bartholomew Strange, he too succumbs at a dinner with many of the same guests as had been present the previous month at Sir Charles' home. This time, Poirot is certain it's murder and an exhumation and examination of Babbington's remains reveal that he too was in fact poisoned. The key to solving the crimes is to identify Ellis, the mysterious butler at Strange's dinner who seems to have vanished.