What is the author's style in Poirot Investigates by Agatha Christie?

Christie uses a conversational writing style in her murder stories. The gaps in plot development are filled by Poirot. She describes the investigation that is then recounted and explained. She provides amusing comments, inserting French words in the speech of the Belgian inspector, enhancing his French character. The vocabulary is factual, focusing on the events that occur along with Poirot's thinking process. His comments provide insights that are personal.