The Mysterious Affair at Styles

The Mysterious Affair at Styles is a detective novel by Agatha Christie. It was written in the middle of World War I, in 1916, and first published by John Lane in the United States in October 1920 and in the United Kingdom by The Bodley Head (John Lane's UK company) on 21 January 1921. The U.S. edition retailed at US$2.00 and the UK edition at seven shillings and sixpence (7/6).

Styles was Christie's first published novel, introducing Hercule Poirot, Inspector (later, Chief Inspector) Japp, and Arthur Hastings (Lieutenant and later, Captain). Poirot is described as "a dear little man", "an extraordinary looking little man" and a "quaint dandyfied little man".

The story is told in first person by Hastings and features many of the elements that have become icons of the Golden Age of Detective Fiction, largely due to Christie's influence. It is set in a large, isolated country manor. There are a half-dozen suspects, most of whom are hiding facts about themselves. The book includes maps of the house, the murder scene, and a drawing of a fragment of a will, as well as a number of red herrings and surprise plot twists.