Hercule Poirot sort of obsessive-compulsive" in Poirot. As mentioned in "Curtain" and "The Clocks", he is fond of classical music, particularly Mozart and Bach. In "The Mysterious Affair at Styles", Poirot operates as a fairly conventional, clue-based and logical detective; reflected in his vocabulary by two common phrases: his use of "the little grey cells" and "order and method". Hastings is irritated by the fact that Poirot sometimes conceals important details of his plans, as in "The Big Four". In this novel, Hastings is kept in the dark throughout the climax. This aspect of Poirot is less evident in the later novels,
Hercule Poirot which Christie contrasts with Hastings' love of autos: this is shown in "The Plymouth Express", "The Mystery of the Blue Train", "Murder on the Orient Express", and "The ABC Murders" (in the TV series, steam trains are seen in nearly all of the episodes). That’s the way of it. Just a case or two, just one case more – the Prima Donna’s farewell performance won’t be in it with yours, Poirot. Confusion surrounds Poirot's retirement. Most of the cases covered by Poirot's private detective agency take place before his retirement to grow marrows, at which time he solves "The Murder