An ailing Poirot returns to Styles with Hastings nearly three decades after solving their first mystery together there in order to prevent an unscrupulous and ingenious serial killer from claiming more victims.

Poirot returns to Belgium for the first time since the Great War. There he revisits a twenty-year-old murder mystery that was never officially solved.

Lucy Crale hires Poirot to solve the murder of her father sixteen years before, and Poirot finds a number of possible suspects who are still alive.

Matthew Davenheim, a rich banker, disappears on a walk from his country house to the village post office, and Inspector Japp of Scotland Yard is put onto the case. Poirot, who has developed an interest in conjuring tricks, bets Japp five pounds that he can solve the mystery without leaving his apartment.

Beside the bodies of three murder victims lies a copy of the ABC Railway Guide.

In an effort to recover his confidence after a rare professional failure, Poirot sets off for the Swiss Alps in pursuit of a missing maid.

Poirot's Christmas is interrupted by Simeon Lee, who believes his life is threatened. Simeon is soon killed and his diamonds stolen.

Hercule Poirot's solicitor, Gilbert Entwhistle, asks Poirot to help solve a riddle and a murder.

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.

Recovering from the horrors of World War I, British Army officer Arthur Hastings hopes to find peace and quiet at a country manor in the English countryside. But when the matriarch dies during the night from strychnine poisoning, Hastings enlists the help of an old friend staying nearby with other war refugees to help solve the murder: former Belgian police detective Hercule Poirot.

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.

A Mrs Ernestine Todd, from Clapham, asks Poirot to help her find her cook, Eliza, who has disappeared. Poirot, who aims to accept only really significant cases, is at first insulted by such a trivial request. However, after he sees the contents of the missing cook's trunk, he decides the case could prove to be worthy of his talents.

Within hours of the Bonfire Night fireworks beginning Poirot finds himself investigating a violent death in Hastings' mews garage.

Poirot discovers a murder in his own block of flats, and goes on the trail of boisterous neighbours and strange nocturnal noises in the lift shaft.

Poirot calls to see the veiled lady of the title (Lady Millicent Castle-Vaughn) at her London hotel. Lady Millicent is about to be married, but a mean blackmailer called Lavington has got hold of a love letter she wrote years before to another man. Lavington wants twenty thousand pounds, and Poirot makes up his mind to recover the letter himself, even if it means impersonating a Swiss locksmith.

Friends and family gather at a dinner party to mark the second anniversary of a woman's death. Meanwhile, Poirot is caught up in a coup d'etat and arrested as a spy, which prevents him from solving a murder at a French restaurant owned by an Italian in Buenos Aires.

Poirot and Hastings are on holiday in Deauville and receive a visit from Paul Renauld, who believes he's being cheated by Chileans. Renauld is kidnapped and his body is later found buried in a new golf bunker. French detective Giraud unwisely challenges Poirot to catch the killer before he can.

After collapsing with heart problems, Hercule Poirot visits a seaside health farm on Burgh Island. While there, the flirtatious heiress Arlena Stewart is found strangled on a secluded beach.

Three single girls share a London flat. The first works as a secretary; the second is an artist; the third, who comes to Poirot for help, disappears believing she is a murderer.

When a vicar chokes to death on a cocktail while attending a party held by actor Sir Charles Cartwright, Poirot initially dismisses the idea of murder but reconsiders when another guest dies in the same manner.

During a village's Hallowe'en party, a young girl boasts of having witnessed a murder from years before. No one believes her tale until her body is found later on in the evening, drowned in the apple-bobbing bucket.

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.

Millionaire business man Benedict Farley, a well known eccentric, consults Poirot about bad dreams he has been having. Mr. Farley has dreamed repeatedly of killing himself. Sadly, he does not follow Poirot's advice. When Farley is found dead, Poirot fails to believe that it is suicide and suspects a murder plot relying on hypnosis.

Poirot tells a surprised Hastings he's decided to retire and suggests they take a holiday in the Lake District. On the way, Hastings befriends a young woman who is missing a collection of valuable miniatures. The case involves a famous writer and a beautiful woman in a sports car, and to the relief of Hastings Poirot's thoughts of retirement soon seem far away.

Poirot visits a garden fete, where a wasps' nest adds to the tension. He meets the son of an old friend who has his girl-friend, a fashion model, with him, and Poirot soon suspects that they are both in danger. He has to solve a mystery which includes cyanide, failing brakes and mixed-up love lives. Meanwhile, Hastings has a new hobby which Poirot finds helpful in cracking the case.