The Italian, whom Poirot soon discovers is a naturalized American, is called in for questioning. Antonio Foscanelli, the Italian, has lived in America for ten years and works for Ford. He tells Poirot that he has little knowledge of the Armstrong case or the Armstrongs. The night of the murder Antonio sat with the American (Hardman) and then went to his compartment. He is awaken in the night by his compartment mate, John Bull, who is groaning. Antonio smokes cigarettes.
Mary Debenham enters the dining car for questioning. Neatly dressed in a black suit, she fulfills Poirot's previous estimate of her. Mary tells Poirot she is twenty-six-year-old and from England. The night of the murder she "went to bed and slept." She woke up at five in the morning with the feeling the train had stopped. When she peered out her door she saw a woman in a scarlet kimono down the corridor. The woman had a shingle cap on and looked tall and thin. Mary does not act terribly affected by the murder, she only saw Ratchett yesterday and hardly noticed him. Poirot asks about Mary's roommate, Greta Ohlsson. Mary tells him she is a nice woman and has a brown, natural wool dressing gown. Poirot confirms that Mary's dressing gown, the same he saw her wear on the train to Stamboul, is a pale mauve. As Mary leaves she tells Poirot that Greta is very worried that she is suspected because she was the last person to see Ratchett alive. Mary saw Greta leave to bring Mrs. Hubbard aspirin at 10:30 and returned about five minutes later. Poirot asks the doctor if Ratchett could have been killed so early. The doctor shakes his head no, Poirot tells Mary to tell Greta she is not suspect.
Poirot discusses why he suspects Mary Debenham with the doctor and M. Bouc. Poirot is suspicious because of the conversation he heard between Mary and Colonel Arbuthnot on the train to Stamboul and because he thinks the murder was planned by a cool and calculated person—like Mary Debenham. The last passenger is called in for questioning, Hildegarde Schmidt, the maid of Princess Dragomiroff. Poirot is kind and gentle with Ms. Schmidt, quite different than his exchange with Mary Debenham. He asks her what she did the previous evening, the night of the murder. Hildegarde went to sleep and was waken by an attendant who told her the Princess needed attention. She put on some clothes and went to the Princess's room, gave her a massage and then read to her until she fell asleep. Afterward, she returned to her compartment and slept. In the corridor, Hildegarde saw the conductor coming out of a compartment two or three doors down from the Princess. The conductor nearly ran into her and briefly apologized. Mrs. Hubbard's bell was ringing, but he did not answer it. Poirot brings in the sleeping car attendants, but Hildegarde does not recognize any of them as the man who bumped into her the night before. Hildegarde tells Poirot the man she bumped into was small and dark.
Hildegarde tears when she talks about the Armstrong case, very moved. She is not the owner of the handkerchief found in Ratchett's room and tells Poirot she does not know who owns it. Poirot notices hesitation in her voice.
Hercule Poirot is one of the great detectives of mystery fiction. He, like other detectives, moves outside of the chaos of a case and employs his resolve and intellect to solve the issue at hand. Poirot's job is to restore the order that has been disrupted on the train by gathering evidence with authority and enough detachment as to allow him to think rationally about the suspects and events of the murder. Unlike if her were still part of the Belgian police force, as a Private Detective, Poirot is independent of official authority and can operate independently. Poirot has intellectual authority and moral authority. As a detective, his objective is to restore order and fight evil and crime.
Poirot's intellectual authority is proven in Chapter 3, Part three where Poirot's thoughts are actually compared with Dr. Constantine and M. Bouc. When the men sit to think about the facts of the case gathered so far, the doctor and M. Bouc are baffled, confused and can hardly focus on the problem at hand. While the men daydream, Poirot sits still and focused, almost motionless until he finds the answer. Poirot's real challenge is to think the murderer, who is smarter than M. Book and Dr. Constantine.