Question:  The Decagon House Murders borrows its basic plot structure from an Agatha Christie novel first published in which year ?
Context: Thirteen at Dinner is a 1985 British-American made-for-television mystery film featuring the Belgian detective Hercule Poirot.  Adapted by Rod Browning from the Agatha Christie novel "Lord Edgware Dies", it was directed by Lou Antonio and starred Peter Ustinov, Faye Dunaway, Jonathan Cecil, Diane Keen and Bill Nighy.  David Suchet, later to play Poirot in the long-running television series entitled "Agatha Christie's Poirot", played the role of Inspector Japp.  Suchet considers his performance as Japp to be "possibly the worst performance of [his] career." Nemesis is a work of detective fiction by Agatha Christie (1890–1976) and first published in the UK by the Collins Crime Club in November 1971 and in the US by Dodd, Mead and Company later in the same year.  The UK edition retailed at £1.50 and the US edition at $6.95.  It was the last Miss Marple novel the author wrote, although "Sleeping Murder" was the last Christie novel to be published. Agatha Christie: Evil Under the Sun is a video game released for the PC and Nintendo Wii, and is the third installment of The Adventure Company's "Agatha Christie" series, developed by AWE Productions, based on Agatha Christie's novel "Evil Under the Sun".  The PC version was released in 2007, and the Wii version one year later. The Decagon House Murders is a 1987 Japanese mystery novel and was the debut work of author Yukito Ayatsuji.  Borrowing its basic plot structure from Agatha Christie's "And Then There Were None" (Christie's book is directly referenced by some of the characters at several points), it tells the story of a group of seven university students who travel to a deserted island that was the scene of a grisly mass murder six months earlier, where events soon turn ominous.  "The Decagon House Murders" belongs to the honkaku subgenre of mystery fiction. The Sittaford Mystery is a work of detective fiction by Agatha Christie, first published in the US by Dodd, Mead and Company in 1931 under the title of The Murder at Hazelmoor and in UK by the Collins Crime Club on 7 September of the same year under Christie's original title.  It is the first Christie novel to be given a different title for the US market.  The US edition retailed at $2.00 and the UK edition at seven shillings and sixpence (7/6). The Royal Castle Hotel is a hotel in Dartmouth, Devon, England.  Guests have included Queen Victoria, Sir Francis Drake, and Mary (who later became Mary II of England).  The hotel was used as a location for the 1984 film, "Ordeal by Innocence", which was based on the 1958 Agatha Christie novel of the same name.  Agatha Christie renamed the hotel the Royal George in 'The Regatta Mystery', a short story that first appeared in The Strand Magazine in 1936 and which currently forms part of the 1991 short story collection Problem at Pollensa Bay.  It holds three stars in the AA rating system and looks across Dartmouth Harbour and the River Dart estuary. Grandmaster is a 2012 Indian thriller film written and directed by B. Unnikrishnan and produced by Ronnie Screwvala and Siddharth Roy Kapur.  Mohanlal stars as Chandrasekhar, an IPS officer who begins investigating a series of murders after receiving an anonymous note.  The plot of the film is partly inspired from the Agatha Christie novel "The A.B.C. Murders".  The supporting cast includes Narain, Priyamani, Anoop Menon, Babu Antony and Jagathy Sreekumar. Lord Edgware Dies is a 1934 British mystery film directed by Henry Edwards and starring Austin Trevor, Jane Carr, and Richard Cooper.  The film was based on the Agatha Christie novel "Lord Edgware Dies", first published in 1933. The Act of Roger Murgatroyd: An Entertainment is a whodunit novel written by Scottish novelist Gilbert Adair first published in 2006.  Set in the 1930s and written in the vein of an Agatha Christie novel, it has all the classic ingredients of a 1930s mystery and is, according to the author, "at one and the same time, a celebration, a parody and a critique not only of Agatha Christie but of the whole Golden Age of English whodunits", but also "a whodunit in its own right, so that those readers who were completely uninterested in literary games of the so-called postmodern type could nevertheless settle down comfortably with a good, gripping and intentionally old-fashioned thriller".  "The Act of Roger Murgatroyd" is also a locked room mystery. And Then There Were None is a mystery novel by English writer Agatha Christie, widely considered her masterpiece and described by her as the most difficult of her books to write.  It was first published in the United Kingdom by the Collins Crime Club on 6 November 1939, as Ten Little Niggers, after the British blackface song, which serves as a major plot point.  The US edition was not released until December 1939; its American reprints and adaptations were all retitled "And Then There Were None", after the last five words in the nursery rhyme "Ten Little Indians".
Answer: 1939