The adventures of Agatha Christie's famous Belgian detective, Hercule Poirot, adapted for television over more than twenty years and covering every Poirot book and short story ever written. This enormous lifelong project starring David Suchet takes the eponymous detective from England to Egypt, from country estate to weekend lodge, from dinner party to train ride, with his good friend Captain Hastings at his side, solving some of the most celebrated murder mysteries ever conceived.
Poirot investigates a strange and gruesome murder of an elderly psychiatrist. Ariadne Oliver is pressed to try and uncover the truth behind two decade-old deaths. They soon find out that their separate investigations are linked and work together to try and solve the mystery.
As a deadly game of chess unfolds in the wake of World War II, Russian grandmaster Dr Ivan Savaranoff meets a shocking end, sending the public spiraling into panic, as suspicion is cast upon Peace Party stalwarts Abe Ryland and Madame Olivier. In one of his toughest challenges yet, Poirot must work out who the villains are from the good people, as a complex plot sees a host of international figures used like pawns by a gang of dangerous dissidents tagged "The Big Four."
As the murders and disappearances stack up one by one, Poirot is joined in his investigations by his old friend Japp, the dogged journalist Tysoe, and struggling actress Flossie Monro, in an attempt to snare the killer and shatter "The Big Four" for good.
Ariadne Oliver is asked to devise a murder hunt for a Devon fête, but her sense of foreboding summons Poirot to the scene. Her fears are realized when, during the fête, the girl playing her murder victim winds up well and truly murdered.
The sleuth falls victim to depression after failing to prevent the murder of a society girl by notorious art thief Marrascaud. His confidence shattered, Poirot eventually returns to work when a lonely chauffeur begs him to find his missing soulmate, the maid of a famous Russian dancer. The investigation takes him to the Swiss Alps, where, against all odds, he stumbles upon a hotel thought to be Marrascaud's hideout - leading to a very personal showdown.
In the post-war climate of the late 1940s, an ailing Poirot reunites with his old friend Captain Hastings at Styles Court, the place where they had solved their first murder together almost thirty years previously. Styles is now a modest guest house run by an elderly couple, and Poirot knows that one of the guests staying there is a heartless serial killer.
The suspects range from a chemist and his invalid wife, a dashing but untrustworthy major, a charming aristocrat, a melancholic middle-aged woman, an unobtrusive birdwatcher, and Hastings' own feisty daughter. With Hastings' assistance, an incapacitated Poirot tries to prevent another murder from occurring, knowing that his own end is nearing.