Johnny Depp headlines a big-name cast in “Murder on the Orient Express.” (Nicola Dove/Twentieth Century Fox)

Agatha Christie’s first mystery, “The Mysterious Affair at Styles,” was rejected by six publishers before finally being published by John Lane in 1920. In it she introduced Hercule Poirot, today the most famous private detective since Sherlock Holmes. By the time of Christie’s death in 1976 at age 85, she herself had become the most popular fiction writer in the world, and “Murder on the Orient Express” her most popular book. It is available in multiple formats, including a facsimile of the original 1934 edition and two audio versions, by Dan Stevens and Kenneth Branagh.

Consequently, most viewers of the new Branagh film of this beloved mystery, which premieres Friday, will already know "who done it," as well as how and why. Still, at least a few people, mainly young, will be encountering this genre classic for the first time, and old Christie fans, such as myself, shouldn't reveal what movie posters would call its Shocking Ending.

The overall plot, though, is utterly simple: On the luxurious Istanbul-to-Calais express, a passenger is found stabbed to death, and Poirot, through the exercise of his “little grey cells,” solves the crime. Virtually everything occurs over just two days, mainly after the train grinds to a halt because of heavy snow in the former Yugoslavia.

The isolation of the characters in “Murder on the Orient Express” creates a tense closet drama. (Twentieth Century Fox)

Like so many Golden Age mysteries, the original novel is essentially a closet drama, one that closely observes the theatrical unities of place, time and action. Christie even divides her book into three sections, corresponding to the acts in a play, and she employs a great deal of dialogue, one of her real strengths as a writer. At the same time, she shows little interest in atmospheric description and makes no serious effort to fathom the psychology of her suspects. For most of the novel’s middle section, Poirot simply interrogates the passengers. Who was the barely glimpsed figure in the red kimono? Whose is a handkerchief embroidered with the initial “H”? The detective then carefully notes the arrangement of the sleeping compartments, the movements of train personnel in the night, the apparent time of the stabbing and the possibility that the original murder plan was altered because of the snow. With far-fetched good luck, Poirot even discovers a partly burned scrap of paper preserving three words that will prove the key to everything.

In summary, “Murder on the Orient Express” sounds unexceptional. So why is it so enthralling to read?

First off, Christie’s prose is lean and brisk, not so much witty as amused, or intrigued, by the curious ways of human beings. At 5 feet 4 inches tall with a head shaped like an egg, her vain and fastidious hero is — according to one young woman — “a ridiculous-looking little man. The sort of little man one could never take seriously.” Only in the 2010 David Suchet film version is the novel reinterpreted as a Dostoevskyan psychodrama in which a spiritually racked Poirot faces moral dilemmas concerning God and justice. By contrast, the written text merely aims to surprise and delight as a tour de force, its brazen imaginative daring rivaled only by the author’s 1926 masterpiece of misdirection, “The Murder of Roger Ackroyd.”

Christie was, of course, unrivaled in the art of narrative sleight of hand. In her fiction, the murderer isn’t just the least likely suspect, but the least likely suspect who has already been cleared and whose innocence seems unquestionable. Nonetheless, just as “The X Files” used to proclaim, “Trust no one,” so Christie always whispers, “Suspect everyone.”

In “Murder on the Orient Express” she revels in showcasing a wide range of characters: the secretive Ratchett, who seems to exude pure evil; the imperious Russian Princess Dragomiroff; the governess Mary Debenham, “the kind of young woman who could take care of herself with perfect ease wherever she went” (a favorite Christie type); the stalwart India hand Colonel Arbuthnot; the young and glamorous Count and Countess Andrenyi; the loudmouthed American Mrs. Hubbard, forever nattering on about her daughter; and half a dozen others, including an Italian car salesman, a proper English valet, a German maid, the Calais coach’s French conductor, and a Swedish nurse and missionary.

Manuel Garcia Rulfo, Daisy Ridley and Leslie Odom Jr. play three of the characters under suspicion in “Murder on the Orient Express.” (Nicola Dove/Twentieth Century Fox)

From having watched trailers for the new film and studied its cast list, I can tell that Branagh — who plays a dramatically mustachioed Poirot — has enlarged the scope of the novel and slightly rejiggered its characters. There are no pistol shots, fistfights, or Hispanic or black passengers in the original book. Mrs. Hubbard is hardly a sexy, merry widow, and Poirot would never go out in the cold without being bundled up. Even the movie’s signature phrase — “My name is Hercule Poirot and I am probably the greatest detective in the world”— actually appears in another Christie novel, “The Mystery of the Blue Train.”

Like the gorgeous 1974 screen version starring Albert Finney, Sean Connery and Ingrid Bergman, Branagh’s “Orient Express” is partly an excuse for today’s big-name Hollywood stars to dress up, look fabulous and chew the scenery. This playful “let’s put on a show” approach works especially well for this deeply theatrical novel. Besides, only on the Orient Express — or, as Poirot tellingly adds, in America — could one find such a colorful variety of nationalities and human types.

The great detective’s final revelations, with all the suspects assembled in the dining car, may strike some readers as almost fantastical. Who cares? In classic mysteries, dazzle is what counts, and realism tends to be inversely proportional to ingenuity. In this case, however, Poirot — the usually inflexible champion of law and order — does act contrary to his principles. Still, justice must sometimes trump traditional ethics. In the end, “Murder on the Orient Express” demonstrates, somewhat paradoxically, the formidable power of love and grief, coupled with unwavering purpose and mutual trust.

Michael Dirda reviews books every Thursday for The Washington Post.

murder on the orient express

By Agatha Christie

William Morrow. 304 pp. Paperback, $9.99