100 years on, it’s no mystery why Agatha Christie’s stories endure

For years, the English village of St. Mary Mead has been the unlikely murder capital of the world. The literary world, that is. Agatha Christie’s fictional hamlet – the home of amateur sleuth Jane Marple – has seen its unfair share of murders, including at the vicarage. 

Last year, 4 million people purchased books written by Christie, known as the Queen of Mystery, to visit the bucolic worlds within her pages. They came to peer into the parlors of country estates where her beloved detectives, Hercule Poirot and Miss Marple, solve seemingly impossible cases. 

Yet there’s still one Christie mystery that remains unsolved. One hundred years since her debut novel, “The Mysterious Affair at Styles,” why does her work remain enduringly popular? Her $2 billion sales lag behind only Shakespeare and the Bible.

To answer that question, perhaps it’s wise to heed the wisdom of Monsieur Poirot: “The simplest explanation is always the most likely.” Readers apparently love her intricately plotted mysteries because they unfurl like astonishing magic tricks in which the illusionist always shows how she did it. But Christie’s admirers say that reducing her stories to mere puzzles is to miss the beating heart of her writing. The mysteries wouldn’t work if we didn’t believe the motives for the murders. Her keen observations about people’s virtues and vices, rooted in a deep sense of justice, have enabled her books to flourish beyond the era in which they were written.

“Christie has a genius for distilling complicated human behavior down into its essence,” says Kate Stine, editor of Mystery Scene magazine and a former director of the Agatha Christie Society, in an email. “She had very firm ideas of right and wrong and while her characters might do pretty much anything, their sins always caught up with them in some fashion.”

Those qualities have made her 66 crime novels lucrative properties for television and cinema adaptations. In the imminent movie “Death on the Nile,” Kenneth Branagh reprises the role of Poirot from his 2017 film “Murder on the Orient Express.” (His dubious mustache has the wingspan of an albatross.) 

Meanwhile, the Belgian detective has been resurrected on the page in a new book series by Sophie Hannah, including the just-released “The Killings at Kingfisher Hill.” Countless crime writers – including Ms. Hannah, David Baldacci, and Gillian Flynn – cite Christie as a formative influence. “It was like nothing I’d read before,” says Gilly Macmillan, author of “What She Knew” and “To Tell You the Truth,” who started reading Christie around age 11. “‘The Murder of Roger Ackroyd’ and the twist absolutely blew me away at the end of that one. It was the first book I read where I realized that the author could withhold something so crucial from you and just slam it down at the end.”  

Christie’s detractors grant that her plotting is akin to watching Garry Kasparov play three-dimensional chess. But they complain that her characters are little more than cardboard cutouts. Moreover, her novels revolve around the sort of upper-class figures who fret that the dying tradition of afternoon teatime portends the doom of civilization. On the other hand, Christie’s defenders commend her crisp style, enlivened by wry wit, as she created archetypes that we all recognize. When Lucy Foley wrote her mystery “The Hunting Party,” her array of suspects was inspired by Christie’s diverse casts of characters. 

“One thing that actually happened when I was writing is that the identity of the murderer changed,” says Ms. Foley. “I would have assumed that that would never happen to Agatha Christie, because she would have known right from the outset. But apparently something that she often did was wait to decide the identity of the murderer later.” 

Although Christie introduced the oddities and frailties of her detectives, they remain fairly inscrutable – much like their famously private creator. In the case of Miss Marple (whose hobbies include knitting and “human nature”) it’s precisely her seeming frailty that makes others underestimate her intelligence. Similarly, readers know very little about the inner life of the fastidious Poirot, whose inclination to tidy and order other people’s rooms would drive even Marie Kondo nuts. 

“The Poirots and the Marples of the world are ‘the instruments of God’ to ensure that justice is done, or seen to be done, on earth as it is in heaven,” says Gillian Gill, author of the biography “Agatha Christie: The Woman and Her Mysteries.” “It’s not civil law. It’s not justice in an institutional manner. It is a weighing of right and wrong.” 

Ruth Ware, whose latest novel “One by One” has been acclaimed as an homage to Christie’s “And Then There Were None,” also picked up on how the author grappled with what justice really is. 

“In one famous example, Poirot colludes in providing the police with a false version of what actually happened, because he agrees that the truth would help no one. In general, though, Christie is not a great believer in extenuating circumstances; motives are very rarely treated as excuses,” writes Ms. Ware via email. “In one of the few examples of her work where a murderer does get away with his crime, Christie herself was so dissatisfied with the ending that she went back and changed it.” 

The Queen of Mystery’s books end with a surprise denouement, the unmasking of one of the seven deadly sins at the root of the crime, and the arrest of the guilty person. 

“It seems to me that Christie is more understanding than judgmental – this goes back to her understanding of human nature and her ability to empathize with her characters,” says Christopher Huang, author of “A Gentleman’s Murder,” via email. “It was, I think, a way of embracing all of humanity, and it made her characters that much richer, that much more believable, and that much more relatable.”