More subtly, we share the thoughts of a group of characters, which includes the killer, in And Then There Were None, but without identifying which thoughts belong to which character (Chapter 11). And in The ABC Murders we think we are sharing the thoughts of a serial killer when, in fact, he is the innocent dupe of the real killer. Less overtly, we are given an insight into the minds of the killer in Five Little Pigs, Towards Zero and Sparkling Cyanide.
Van Dine 10. The culprit must turn out to be a person who has played a more or less prominent part in the story.
Never one to cheat her readers, this is one of the Rules that Christie did not break. She never unmasked the second cousin of the under-housemaid as the killer in the last chapter. Taking her cue from ‘The Purloined Letter’, the Queen of Crime hid her murderers in plain sight.
Van Dine 11. A servant must not be chosen as the culprit.
This is not mere social prejudice (although there is plenty of that in the work of Van Dine himself) but a practical solution to the problem of the unmasking, in the last chapter, of a member of the domestic staff whose presence in the novel was fleeting at best. Consider how Christie overcame this stricture. Kirsten Lindstrom in Ordeal by Innocence is, strictly speaking, a domestic servant but her significance to the Argyle family can be interpreted as placing her outside this category. But it is as a servant that we meet, and continue to perceive, her. This same consideration applies to Miss Gilchrist in After the Funeral; witness the telling scene at the denouement when she bitterly recriminates the Abernethie family. Gladys, in A Pocket Full of Rye, is a clearer example of domestic servitude; indeed, it is her status as such that makes her a vital element of Lance’s murderous plan. In defence of Christie’s oft-criticised attitude to domestic servants, it is the subsequent death of Gladys that causes Miss Marple to arrive at Yewtree Lodge to avenge the death of a foolish and gullible former maid. And the closing pages of the book, as Miss Marple reads a letter from Gladys written just before her murder, are very affecting. The same plot device, and much of the same plot, can be seen in the earlier short story ‘The Tuesday Night Club’
Van Dine 17. A professional criminal must never be shouldered with the guilt in a detective novel.
Apart from brief – and not totally convincing – forays into organised crime in The Big Four, The Secret of Chimneys and At Bertram’s Hotel, no use is made of a professional criminal in Christie’s solutions.
Van Dine 12. There must be but one culprit no matter how many murders are committed.
Murderous alliances are a feature of Christie’s fiction beginning with The Mysterious Affair at Styles and continuing with The Murder at the Vicarage, Death on the Nile, One, Two, Buckle my Shoe, Evil under the Sun, The Body in the Library, Sparkling Cyanide and Endless Night. Cat among the Pigeons and, to a lesser degree, Taken at the Flood, feature more than one killer working independently of each other; The Hollow features an unusual and morally questionable, collusion; and, of course, Murder on the Orient Express features the ultimate conspiracy.
The murder method
Christie never resorted to elaborate mechanical or scientific means to explain her ingenuity, and much of her popularity and accessibility lies in her adherence to this simplicity. Many of her last-chapter surprises can be explained in a few sentences. Once you have grasped the essential fact that the corpse identified as A is, in fact, Corpse B and vice versa everything else falls into place; when you realise that all twelve suspects conspired to murder one victim all confusion disappears; when it dawns that the name Evelyn can mean a male or a female little further explanation is necessary.
Van Dine 14. The method of murder, and the means of detecting it, must be rational and scientific.
Knox 4. No hitherto undiscovered poisons may be used, nor any appliance which will need long scientific explanation at the end.
While Christie uses poisons as a means of killing characters more than most of her contemporaries, she uses only those that are scientifically known. But, that said, thanks to her training as a dispenser, she had more knowledge of the subject than many of her fellow writers and was familiar with unusual poisons and the more unusual properties of the common ones. Her first novel, The Mysterious Affair at Styles, depends for its surprise solution on knowledge of the properties of strychnine, but this is not unreasonable as the reader is fully aware of the poison used. In fact, there is a graphic description of the death of Mrs Inglethorpe and a discussion of the effects of, and the chemical formula for, strychnine. Taxine in A Pocket Full of Rye, ricin in ‘The House of Lurking Death’ from Partners in Crime, thallium in The Pale Horse and physostigmine in Crooked House are just some of the unusual poisons featuring in Christie. Fictitious drugs such as Serenite in A Caribbean Mystery, Calmo in The Mirror Crack’d from Side to Side and Benvo in Passenger to Frankfurt also feature, but as the plot does not turn on their usage, they merely bend, rather than break, Knox’s Rule.
To be avoided
Some of these items are mere personal prejudice; there is no good reason why cigarettes or twins, for instance, cannot be a clue, or even a main plot device, provided that the reader has been properly prepared for them. With all of these the important point is the originality of the approach in utilising them – and this Christie had in full measure and overflowing.
Van Dine 13. Secret societies have no place in a detective story.
Many readers, including probably the author herself, would wish that The Big Four had never found its way between hard covers. Cobbled together at the lowest point in her life (after the death of her mother, the request for a divorce from her husband and her subsequent disappearance) with the help of her brother-in-law, Campbell Christie, this collection of linked short stories was re-edited into a novel. The ‘secret society’ bent on world domination that it features was, mercifully, a one-off aberration on Christie’s part. The Seven Dials Mystery features an equally preposterous secret society, albeit one with a Christie twist. The Pale Horse, one of the best books of the 1960s, features a mysterious organisation, Murder Inc., that seems to specialise in remote killing, but a rational and horribly plausible scheme is revealed in the closing chapters.
Knox 5. No Chinamen must figure in the story.
This comment is not as racist as it may first appear. At the time of its writing Orientals in fiction were perceived, under the general heading of ‘The Yellow Peril’, as the personification of everything undesirable. A more detailed discussion of the subject can be found in Colin Watson’s Snobbery with Violence (1971), an investigation of the social attitudes reflected in British crime fiction of the twentieth century, but suffice it to say that the white-slave trade, torture and other ‘unspeakable acts’ were the accepted fictional norms at the time for any character of Oriental extraction. This Rule was included to raise the literary horizon above that of the average opium den. Unfortunately, Christie succumbs to stereotype in The Big Four where, amid cringe-inducing scenes with Oriental characters and ‘speech’, the chief villain, ‘the greatest criminal brain of all time’, is Chinese. But these stories pre-dated Knox. Apart from The Big Four, and the more politically correct Poirot case ‘The Lost Mine’, no ‘Chinamen’ play a part in any of Christie’s detective novels.