Poirot is confused by the interview with Ms. Debenham. He tells M. Bouc that he believes this was a premeditated crime, rather than a crime of passion, and he was trying to shake Ms. Debenham’s self-possession. Given that she and Colonel Arbuthnot have a prior relationship, he expected them to provide alibis for each other, but instead their alibis are confirmed by strangers.
Poirot interrogated Mary Debenham in a heavy-handed way because he believes she has the “cool, resourceful brain” necessary to pull of the murder, which he now believes was premeditated. He also raises an unconventional aspect of the crime: strangers offering alibis for each other. Particularly in Arbuthnot and Ms. Debenham’s case, the two have kept scrupulously apart since their time together on the train to Istanbul.
Poirot has only one witness left to call: Hildegarde Schmidt, who is Princess Dragomiroff’s lady’s maid. Poirot was adversarial with Ms. Debenham, but with Hildegarde “he was at his kindest and most genial, setting the woman at her ease.” He also slips into German so that Hildegarde can converse in her native language.
Poirot again calibrates his approach to the witness, finding a kind approach the best way to gather information from Hildegarde Schmidt. His status as an “international detective” pays off as well, as he has enough German to interview her in her native language, setting her further at ease.
Hildegarde maintains that she doesn’t know anything. She says she was called to attend to the Princess the previous night. When she notes that she doesn’t like to wear a dressing gown in the presence of the Princess, Poirot gently interrupts to compliment her “scarlet” dressing gown. She replies that hers is dark blue. According to Hildegarde, after massaging the Princess, she returned to her cabin and slept.
Having put Hildegarde at ease, Poirot hopes to surprise her by acting as if he knows more than he does: namely, the color of her dressing gown. Poirot’s efforts to build rapport lead to a situation where he adds details that it would be easy for the suspect to confirm, provided that the details are true.
Poirot asks whether Hildegarde saw a woman in a scarlet dressing gown and her eyes “bulge,” but she denies it. However, she did see a conductor coming out of one of the compartments and walking swiftly past her in the other direction, a fact that M. Bouc particularly treats as sensational. The conductor passed her moving towards the dining car, ignoring a ringing bell.
Hildegarde, unbalanced by the suggestion about her dressing gown, reveals that she knows more than she lets on, bulging her eyes as Poirot asks about the scarlet kimono. She also reveals that there was a conductor in one of the compartments, which as M.Bouc’s surprise shows, is new information. The fact that there was a conductor moving away from the ringing bell either contradicts Pierre Michel’s account or suggests that there was another conductor, or someone dressed as a conductor, in the Paris train car.
M. Bouc sends for the three conductors so that Hildegarde can identify the man she saw. In the meantime, Poirot asks whether the handkerchief found in Ratchett’s room is hers. Hildegarde responds “I? Oh, no, Monsieur,” which Poirot finds odd, hearing a “nuance of hesitation” in it.
There are three conductors on the train attending to the Bucharest, Athens, and Paris train cars. If none of these resemble the man Hildegarde saw, it may point to a stranger disguised as a conductor. Poirot also follows up on the monogrammed handkerchief, as the “H” initial might point to “Hildegarde.” Hildegarde denies ownership saying “I? Oh, no” which Poirot detects as implying that she knows it belongs to someone else.
When the three conductors, including Pierre Michel, arrive, Hildegarde claims that none of them are the man she saw. Asked to describe the man, Hildegarde remembers a small, dark man, who said “pardon me” in a feminine voice.
None of the conductors resemble the conductor that Hildegarde saw. She describes instead, almost to the letter, the man that Hardman had suggested as the assailant that Ratchett was expecting.