Hercule Poirot's assistant, Hastings, calls him down to Acapulco in Mexico where he can write his memoirs but Hastings drags him to a party populated with Hastings' new friends. There's Janet Crisp - the writer, Daisy Eastman and her daughter 'Egg', Ricardo Montoya, Dr. Strange, Miss Milray the housekeeper and Charles Cartwright the famous American actor. But at the party another guest - Rev. Babbington - dies from poisoning and when Dr. Strange also dies from poisoning, Poirot must swing into action before the serial killer strikes again...