Poirot's first appearance was in The Mysterious Affair at Styles ( published 1920 ) and his last in Curtain ( published 1975, the year before Christie died ).

Although Hastings remains the most popular of Poirot's sidekicks, his appearance in only eight of the thirty-three Poirot novels indicates that he no longer served Christie's literary purpose.

The book also features the first appearance of Poirot's valet, George.

One thing that is consistent about Poirot's retirement is that his fame declines during it, so that in the later novels he is often disappointed when characters ( especially younger characters ) recognize neither him nor his name:

Hastings, a former British Army officer, first meets Poirot during Poirot's years as a police officer in Belgium and almost immediately after they both arrive in England.

The novel is set in England during World War I at Styles Court, an Essex country manor ( also the setting of Curtain, Poirot's last case ).

It is generally believed that Christie wrote Curtain ( Hercule Poirot's last mystery, which concludes the sleuth's career and life ) and Sleeping Murder during World War II to be published after her death, and that Sleeping Murder was most probably written sometime during the Blitz, which took place between September 1940 and May 1941.

Due to its early date of composition, Curtain takes no account of Poirot's later career.

Poirot's misery in the run-down guesthouse, and Mrs Oliver's observations on the life of a detective novelist, provide considerable entertainment in the early part of the novel.

In the collection, Christie charts some of the cases from Hercule Poirot's early career, before he was internationally renowned as a detective.

Inspector Japp gives some insight into Poirot's career with the Belgian police when introducing him to a colleague:

Perhaps this is enough evidence to suggest that Poirot's police career was a successful one.

Towards the end of his career it becomes clear that Poirot's retirement is no longer a convenient fiction.

Like those of Miss Lemon and Arthur Hastings, the role of Inspector Japp in Poirot's career has been exaggerated by adaptations of Christie's original novels ; specifically by the TV series Agatha Christie's Poirot, where these characters are often introduced into stories that did not originally feature them.

Among Poirot's most significant personal attributes is the sensitivity of his stomach:

" I suppose you know pretty well everything there is to know about Poirot's family by this time ".

The history of the Countess is, like Poirot's, steeped in mystery.

There is a great deal of confusion about Poirot's retirement.

There is specific mention in " The Capture of Cerberus " to the fact that there has been a gap of twenty years between Poirot's previous meeting with Countess Rossakoff and this one.

It is therefore better to assume that Christie provided no authoritative chronology for Poirot's retirement, but assumed that he could either be an active detective, a consulting detective or a retired detective as the needs of the immediate case required.

In Cat Among the Pigeons Poirot's entrance is so late as to be almost an afterthought.

She is also the only one in Poirot's universe to have noted that " It ’ s not natural for five or six people to be on the spot when B is murdered and all have a motive for killing B.

It is also revealed that the " window cleaner " was actually an actor in Poirot's employ, though Poirot brags that he did " witness " Roberts kill Mrs. Lorrimer in his mind's eye.

Poirot's focus is upon a wasp that has been seen in the compartment and which provided evidence for the original theory of the cause of death.

It is narrated by Dr. James Sheppard, who becomes Poirot's assistant ( a role filled by Captain Hastings in several other Poirot novels ).

He then lays out a completely reasoned case that the murderer is in fact Dr. Sheppard, who has not only been Poirot's assistant, but the story's narrator.

One is Poirot's use of ratiocination, the other is the channel of gossiping, practised by almost all inhabitants of King's Abbott, in particular, Caroline.

In this adaptation Japp — not Sheppard — is Poirot's assistant, leaving Sheppard as just another suspect.

However, the device of Dr. Sheppard's journal is retained as the supposed source of Poirot's voice-over narration and forms an integral part of the dénouement.

David Suchet confirmed that the filming of the last five novels, for series 13, begins on 15 October 2012, with Curtain: Poirot's Last Case shooting first out of the remaining books.

Poirot's last actions were to write the confession and await his death, which he accelerated by moving amyl nitrite phials out of his own reach, seeking to avoid the traditional arrogance of the murderer where he might come to believe that he had the right to kill those he deemed it necessary to eliminate.

The mystery of who left the note on Poirot's pillow is solved when one of the housemaids confesses that she heard Lee-Wortley and his " sister " discussing getting Poirot out of the way and that something had been put in the pudding, causing her to think they planned to poison him.

The lights suddenly go out and Mrs Maltravers clasps Poirot's hand.

Poirot sends his valet out investigating and finds an address which confirms Poirot's suspicions of where it would be and what he would find there.

The next day, having sorted out Joseph Aaron's problem, Poirot and Hastings return to Ebermouth but, at Poirot's insistence, this time by train.

The visual style of these later episodes was noticeably different from earlier episodes: particularly, austere art deco settings and decor, widely used earlier in the series, were largely dropped in favour of more lavish settings ( epitomised by the re-imagining of Poirot's home as a larger, more lavish apartment ).

But Poirot is helpless: the letter has arrived three days later than it was supposed to, just because ABC misspelled Poirot's address.

Hastings's appearances in Poirot's later novels are restricted to a few cases in which he participates on his periodic returns to England from Argentina ; Poirot comments in The ABC Murders that he enjoys Hastings's visits because he always has his most interesting cases when Hastings is with him.

In other respects there is very little personal detail regarding him in these novels, until Curtain: Poirot's Last Case, which is presumed to take place a great many years later ; with his wife now dead, Hastings rejoins Poirot at Styles to help Poirot tackle one last case, Poirot dying of a heart attack at the conclusion but leaving Hastings a confession explaining his role in events.

Curtain: Poirot's Last Case is a work of detective fiction by Agatha Christie and first published in the UK by the Collins Crime Club in September 1975 and in the US by Dodd, Mead and Company later in the same year.

The novel's plot is based on the 1923 Poirot short story The Plymouth Express ( much later collected in book form in the US in 1951 in The Under Dog and Other Stories and in the UK in 1974 in Poirot's Early Cases ).

The American version of the book, published one year later, featured an additional three stories which did not appear in book form in the UK until 1974 with the publication of Poirot's Early Cases.

Although the stories contained within the volume had all appeared in previous US collections, the book also appeared there later in 1974 under the slightly different title of Hercule Poirot's Early Cases in an edition retailing at $ 6. 95.

Poirot places advertisements in the newspaper enquiring as to the whereabouts of Eliza and several days later he is successful in locating her when she visits Poirot's rooms.

Poirot's earlier conversation included several traps for the man, including the time of Langton's appointment – Poirot already knew Langton was due to return at eight-thirty but Harrison said it was later, by which time he hoped to have committed the deed.