Murder on the Orient Express was first published in 1934, by which point Agatha Christie was already well-known. In fact, the murder mystery author had made headlines herself when she mysteriously disappeared in 1926, inciting an organized search and front-page headlines. Eleven days later, Christie was found at a hotel in Harrogate, where she'd checked in under the name of her then-husband's mistress. She seemed to have memory loss and couldn't provide an account of why she left or what she'd been doing. The exact reasons for her disappearance and the circumstances surrounding it still aren't known.

Christie, the “Queen of Crime,” is renowned for her mystery books. Poirot is one of her most famous detective characters, appearing in more than 30 books, the first of which was The Mysterious Affair at Styles (1920). Murder on the Orient Express is the 10th novel in Poirot’s investigations, with its format focused on the crime more than detailed descriptions of the detective himself. It is presumed that the reader already knows Poirot, and this knowledge is mirrored by the fact that many characters in the book already know him—he is, at this point, a famous detective, both in the fictitious world and the real world.