England, December 1926. Although her personal life is in tatters, the famous writer Agatha Christie decides to leave everything behind to help unravel an unsolved murder committed on a train six years ago, unable to imagine the disproportionate consequences that such a selfless act will cause.
At the insistence of Ruth Van Rydock, an old schoolfriend who is convinced that there is something wrong, Miss Marple agrees to visit 'Stonygates', the country house of Ruth's sister.
An unlikely friendship unfolds between a young deaf boy, Wesley, and a fugitive criminal who takes refuge in an abandoned barn on the family’s rural North Dakota farm.
In Acapulco, Hercule Poirot attends a dinner party in which one of the guests clutches his throat and suddenly dies. The causes seem to be natural until another party with most of the same guests produces another corpse.
A series of murders is committed in Nice on the French riviera. The commissaire Carella is in charge and tries to find a missing link between all these murders.