The American lady, Mrs. Hubbard, is all in a tizzy, so Poirot sees her next.
Before the questioning begins, Mrs. Hubbard drops some "vurry important" information on Poirot (2.4.2): the murderer was in her own compartment last night.
The way Mrs. Hubbard tells it, she could feel someone was in her compartment, so she closed her eyes and froze up, and then she called for the conductor. When he arrived, no one else was there. She claims the man got away.
Mrs. Hubbard told the conductor to check the door, and, sure enough, it wasn't bolted.
To prove that the man was in her compartment, she pulls a button from a Wagon Lit attendant's uniform out of her overstuffed bag. She knows that the man dropped it, because it was on top of a magazine she had been reading. The conductor who came in to check it didn't go anywhere near her magazine.
From there, Poirot moves on to questioning Mrs. Hubbard. Here's what we learn:
Mrs. Hubbard had made sure the door was bolted before she went to sleep by asking the Swedish woman to check it. The woman had come by her room to ask for aspirin.
Hubbard mentions that the Swedish woman had gone into Ratchett's room by mistake and saw him in there. He apparently made a lewd comment to her.
Hubbard says that Ratchett snored, but she didn't hear any snoring after she noticed the man in her compartment.
Mrs. Hubbard claims not to know the Armstrong family personally, but says she did know of the case.
She does not own a scarlet dressing gown.
Mrs. Hubbard also admits to hearing a woman's voice coming from Ratchett's compartment. She had thought it best not to say anything about it before, since it's not a "very nice thing to speak about" (2.4.97).
She says she heard the woman's voice before Ratchett was dead.
The handkerchief, she says, is not hers. The one Poirot found is expensive, and hers isn't.