Illustrious crowd is present at the 'Peace Party'. Poirot reunites with old friend, Japp, at this event. The American tycoon, and hearty backer of the Party, Abe Ryland, fronts the event, which climaxes in an exciting game of chess, where he takes on the reclusive Russian Grandmaster, Dr. Ivan Savaranoff. But the match has barely begun, when suddenly Savaranoff collapses dead. Panic quickly spreads when Ryland suspiciously disappears.

13 years ago, a couple tragically died, but the question has always remained - did the husband, General Ravenscroft, shoot the wife, or did the wife, Molly, kill the husband? Present day, Poirot is onto solving Dr Willoughby's, father's case. Poirot's old crime-writing friend, Ariadne Oliver, is dealing with a case of tracking down the truth via half-remembered stories from 13 years ago about the Ravenscroft. When these two puzzles are pieced together, the truth reveals itself.

Desperate to catch infamous art thief Marrascaud, the Metropolitan Police build what they imagine is a perfect trap, but when a murder and robbery take place, it pushes Poirot into the pits of depression. Only when a lonely chauffeur begs the detective to find his missing true love, Poirot feels he can return to his work. The quest takes Poirot to the Swiss Alps, where fate plays a hand, against all odds and Poirot finds himself in a game of cat-and-mouse with a villain he fears and despises.

Confined to a wheelchair and crippled with arthritis, the now elderly, Hercule Poirot is reunited with his old companion, Captain Hastings, back where it all began, Styles, to solve their last investigative case.