Agatha Christie 
The Mysterious Affair at Styles 

British author Agatha Christie wrote a detective book titled The Mysterious Affair at Styles in 1916, in the middle of the First World War. It introduced Arthur Hastings, Inspector (later Chief Inspector) Japp, and Hercule Poirot. The elderly owner of Styles Court, Emily Inglethorp, is found dead on July 18, 1918. Strychnine had been used to poison her. On his sick leave, Arthur Hastings, a Western Front soldier who is a guest at this country manor, sets out to ask Hercule Poirot for assistance.Poirot finds out that John would receive the manor property in accordance with his father's will once Emily passes away. However, she will decide how her money is split up in her own will, which she updates at least once a year. Alfred, the beneficiary of her most recent will, will now get her wealth.John is cleared of the crime by Poirot's investigations. He proves that Alfred Inglethorp carried out the murder with the assistance of his cousin Evelyn Howard. They made Emily's customary nighttime medication, which they received from her sleeping powder, fatal by adding bromide to it.On the day of the murder, Emily was upset because she discovered a letter on Alfred's desk while looking for stamps.