During the Golden Age of mystery fiction, four women—Agatha Christie, Dorothy L. Sayers, Ngaio Marsh, and Margery Allingham—were dubbed the Queens of Crime. But let’s be honest, we all know who among that group really deserved the crown. No other mystery writer before or after Agatha Christie can match her literary reputation when it comes to commercial sales or creative plots.

Over her long literary career, Christie came up with an astounding number of cleverly conceived crime novels that have thrilled and delighted generations of readers. Today, with more than two billion copies of her books sold around the globe, Christie is still the world’s best-selling novelist. In fact, she is only outsold by the Bible and Shakespeare. Between 1920 and 1975, Christie wrote 66 crime novels, 14 short story collections, a half dozen or so romantic novels, as well as number of plays, including Mousetrap, which began its run in London on November 25, 1952 and continues to play to mesmerized audiences today.

No author before or since has been able to match Christie’s skill at constructing ingenious mystery plots. From the least likely suspect to the most likely suspect, she excelled at cooking up some of the most deviously crafty mysteries ever devised. As if this were not enough, Christie further demonstrated her literary prowess by deftly seeding the clues to solving the crime into her plots in such a way that even if the reader doesn’t successfully guess the identity of the murderer, when presented with the solution to the crime, they still wind up saying “I should have thought of that!” Or, as noted Christie critic and award-winning mystery novelist Robert Barnard put it, “You always want to kick yourself at the end rather than the author.”

Critics of Christie often target what they like to call her unembellished brand of characters, but in doing so, these same critics miss how brilliantly Christie uses this “flaw” as a way of further pulling the wool over readers’ eyes. When presented with one of Christie’s stock characters—like the hale and hearty military man or the gossipy village spinster—readers will fill in any blanks with their own expectations. This then allows Christie to later turn the tables on the reader by giving this self–same stock character some unique twist the reader never expected.

Other critics, up to and including Raymond Chandler, have tried to marginalize Christie’s literary output by describing her as a “cozy” mystery writer. It is true that Christie did much to popularize the concept of murder most civilized, be it in a small village or an exotic foreign locale. However, while Christie did eschew the use of graphic language and gritty violence in her novels, she had a very clear and concrete understanding of just how high the societal stakes were when it comes to murder. Seeing that justice was served is at the heart of each and every one of her books.

This isn’t to say that everything Christie wrote was pure literary gold. Christie admitted herself to churning out a few clunkers; she was particularly vexed over the course of her writing career with the end result of The Mystery of the Blue Train. But given the prodigious number of her novels, not to mention plays and short stories, she wrote over almost six decades of work, one or two less-than-stellar efforts can easily be forgiven and forgotten.

In the end, I believe the key reason for Christie’s amazing success with mystery readers is that she never forgot exactly why she wrote mysteries: to entertain readers. Unlike some of her fellow crime novelists (yes, I’m talking about you, Dorothy L. Sayers), Christie had no interest in trying to marry a detective tale with a literary novel. All Christie wanted to do was come up with a story that would keep someone happily turning the pages whether they are sunning themselves on the beach while on vacation or comfortably ensconced in their favorite armchair at home. Given this objective, Christie succeeded beyond her wildest expectations.