An ailing Poirot returns to Styles with Hastings nearly three decades after solving their first mystery there in order to prevent a serial killer from claiming more victims.
While in Belgium, Poirot relates to Chief Inspector Japp a case from his early days in the Belgian police force that nearly eluded the brilliance of his 'little grey cells.'
Poirot's pursuit of an infamous art thief leads him to a snowbound hotel in the Swiss Alps, where he is met with a plethora of mysteries and the reappearance of a familiar face from the past.
Poirot investigates the murder of a shady American businessman stabbed in his compartment on the Orient Express when it is blocked by a blizzard in Croatia.
A wealthy American heiress honeymooning on a Nile cruise ship is stalked by a former friend, whose boyfriend she had stolen before making him her new husband.
Poirot's rehabilitative health retreat on an island resort becomes an even more stimulating mental exercise when a flirtatious film star is found strangled on a nearby beach.
Elinor Carlisle seems to be the obvious murderer of her ailing aunt and the beautiful romantic rival who broke up her engagement, but Poirot uncovers darker motives.