Hercule Poirot available to solve mysteries at an English country house. At the time of Christie's writing, it was considered patriotic to express sympathy towards the Belgians, since the invasion of their country had constituted Britain's "casus belli" for entering World War I, and British wartime propaganda emphasised the "Rape of Belgium". Poirot first appeared in "The Mysterious Affair at Styles" (published in 1920) and exited in "Curtain" (published in 1975). Following the latter, Poirot was the only fictional character to receive an obituary on the front page of "The New York Times". By 1930, Agatha Christie found Poirot "insufferable", and, by
Agatha Christie the Christie family gave their "full backing" to the release of a new Poirot story, "The Monogram Murders", which was written by British author Sophie Hannah. Hannah later released a second Poirot mystery, "Closed Casket", in 2016. Christie's reputation as "The Queen of Crime" was built upon the large number of classic motifs that she introduced, or for which she provided the most famous example. Christie built these tropes into what is now considered classic mystery structure: a murder is committed, there are multiple suspects who are all concealing secrets, and the detective gradually uncovers these secrets over the course