The Big Four is a work of detective fiction by Agatha Christie, first published in the UK by William Collins & Sons on 27 January 1927[1] and in the US by Dodd, Mead and Company later in the same year.

Christie would have realized that The Big Four was an inferior novel and went to work writing The Murder of Roger Ackroyd for the new publisher.

It sold despite not being a traditional murder mystery, being a tale of international intrigue and espionage, and opening the possibility of more spy fiction from Christie.

In 1942, Christie wrote to her agent, Edmund Cork of Hughes Massie, asking him to keep a manuscript in reserve (probably Sleeping Murder) and statedI have been, once, in a position where I wanted to write just for the sake of money coming in and when I felt I couldn't – it is a nerve wracking feeling.

When Hastings jokingly calls it "The Mystery of the Big Four," the man begins speaking about an international crime cartel of that name.

The novel is not set in the manor house or a rural area like a number of its predecessors, nor do the characters represent the British gentry.

Poirot does not track down a murderer; he must face and expose a supranational association of high-ranking personalities who are working towards world domination.

[7] Jeremy Black, a historian, points out that a number of Agatha Christie's novels of the interwar period record the standard fears of affluent society in the era.

This is an element present in her literary work and absent in the adaptations of Agatha Christie for television and film.

[11] Black adds that Christie's work is, in its way, typical of the literature of the interwar period, much of which reflected a concern about foreign threats and links between domestic and international challenges.

[11] Li Chang Yen is both a creature of sinister Orientalism and an echo of an earlier literary character: Fu Manchu by Sax Rohmer.

In The Mystery of Dr. Fu-Manchu (1913), the eponymous character is presented as a figure behind Anti-Western actions in British Hong Kong and Chinese Turkestan.

He is striking against Western politicians and administrators who are aware of the secret geopolitical importance of Tonkin, Mongolia, and Tibet, using these areas as a keyhole to the gate of the Indian Empire.

[5] The Times Literary Supplement review of the book publication struck a positive although incorrect note in its issue of 3 February 1927 when it assumed that the different style of the book from its immediate predecessor, The Murder of Roger Ackroyd, was a deliberate ploy: "M. Poirot, the Belgian detective who has figured in others of Mrs Christie's tales, is in very good form in the latest series of adventures.

(sic) such a puzzling problem for the reader of detective fiction is one that a writer cannot easily employ a second time, and indeed the present story is not so much the clearing up of a mystery as a recital of Poirot's encounters with one of those familiar groups of international crooks of almost unlimited power who seek to dominate the world."

[13] The New York Times Book Review of 2 October 1927 outlined the basics of the plot and stated "'Number Four' remains a mystery almost to the end.

This, of course, makes it more difficult for the detective to guard against attack and to carry on his investigation, and it provides most of the thrills of the story.

"[14] The reviewer in The Observer of 13 February 1927 did not expect originality when reading a book dealing with the themes of The Big Four, but did admit that "When one opens a book and finds the name Li Chang Yen and is taken to subterranean chambers in the East End 'hung with rich Oriental silks', one fears the worst.

[16] Robert Barnard: "This thriller was cobbled together at the lowest point in Christie's life, with the help of her brother-in-law.

This was translated from the edition first published in France by Emmanuel Proust éditions in 2006 under the title of Les Quatre.

The film premiered on ITV on 23 October 2013 and on PBS on 27 July 2014 in the United States;[18] it also guest-starred Sarah Parish, Patricia Hodge, Tom Brooke, Nicholas Burns, and Simon Lowe.

Suchet's former co-stars Hugh Fraser, Philip Jackson, and Pauline Moran reprised their roles as Hastings, Japp, and Miss Lemon.