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,
Poirot Investigates accepted Lane's strictures about what would be published by them, but by the time of "Poirot Investigates" Christie insisted that their suggested title of "The Grey Cells of Monsieur Poirot" was not to her liking and that the book was to be included in the tally of six books within her contract. The Bodley Head opposed this because the stories had already been printed in "The Sketch". Christie held out and won her case. This was the first Christie book to carry no dedication. The dustjacket front flap of the first edition carried no specially written blurb. Instead it carried