The action takes place mainly on board an old wooden-walled battleship, HMS ''Battledore,'' which has been purchased by a Trust for the rehabilitation of young criminals, and intended by the founder to ''put backbone into young jellyfish.''
Emily Boynton, the stepmother to three children, blackmails the family lawyer into destroying a second will of her late husband that would have freed the children from her dominating influence. She takes herself, the children, and her daughter-in-law on holiday to Europe and the Holy Land. At a dig, Emily is found dead and Hercule Poirot investigates.
Daryl Zero is a private investigator and—along with his assistant, Steve Arlo—he solves impossible crimes and puzzles. Although Daryl's a master investigator, he doesn't know what to do with himself when he's not working; he has no social skills, writes bad music and drives Steve crazy.
A mystery writer is intrigued by the tale of notorious criminal Dimitrios Makropolous, whose dead body was found washed up on the shore in Istanbul. He decides to follow the career of Dimitrios around Europe, in order to learn more about the man. Along the way he is joined by the mysterious Mr. Peters, who has his own motivation.
Actress Jane Wilkinson wants a divorce, but her husband, Lord Edgware, refuses. She convinces Hercule Poirot to use his famed tact and logic to make her case. Lord Edgware turns up murdered, a well-placed knife wound at the base of his neck. It will take the precise Poirot to sort out the lies from the alibis - and find the criminal before another victim dies.