Written in 1916 during The First World War, &quot;The Mysterious Affair at Styles&quot; was British author Agatha Christie&rsquo;s debut mystery novel. The novel was released in the United States in 1920, then in the United Kingdom in 1921.&nbsp;<br /><br />Set at Styles Court outside of Essex, &quot;The Mysterious Affair at Styles&quot; introduces Christie&rsquo;s heroic Belgian sleuth, Hercule Poirot, Inspector (later, Chief Inspector) Japp, and Lieutenant Hastings (later, Captain). When Detective Poirot is summoned to Styles Court to investigate the mysterious death of its rich elderly owner, Emily Inglethorp, he interrogates several suspects before eventually solving the crime.&nbsp;<br /><br />In 1990, the classic mystery was adapted as an episode of the television series Poirot, directed by Ross Devenish and starring David Suchet as Poirot.