# The Mystery of the Blue Train/Chapter 23

CHAPTER XXIII
A NEW THEORY
It was exactly eleven o'clock when Poirot presented himself at Van Aldin's hotel. He found the millionaire alone.
"You are punctual, M. Poirot," he said, with a smile, as he rose to greet the detective.
"I am always punctual," said Poirot. “The exactitude—always do I observe it. Without order and method——"
He broke off. "Ah, but it is possible that I have said these things to you before. Let us come at once to the object of my visit."
"Your little idea?"
"Yes, my little idea." Poirot smiled.
"First of all, Monsieur. I should like to interview once more the maid, Ada Mason. She is here?"
"Yes, she's here."
"Ah!"
Van Aldin looked at him curiously. He rang the bell, and a messenger was dispatched to find Mason.
Poirot greeted her with his usual politeness, which was never without effect on that particular class.
"Good afternoon. Mademoiselle," he said cheerfully Be seated, will you not, if Monsieur permits."
"Yes, yes, sit down, my girl," said Van Aldin.
"Thank you, sir," said Mason primly, and she sat ​down on the extreme edge of a chair. She looked bonier and more acid than ever.
"I have come to ask you yet more questions," said Poirot. "We must get to the bottom of this affair. Always I return to the question of the man in the train. You have been shown the Comte de la Roche. You say that it is possible he was the man, but you are not sure."
"As I told you, sir, I never saw the gentleman's face. That is what makes it so difficult."
Poirot beamed and nodded.
"Precisely, exactly. I comprehend well the difficulty. Now, Mademoiselle, you have been in the service of Madame Kettering two months, you say. During that time, how often did you see your master?"
Mason reflected a minute or two, and then said:
"Only twice, sir."
"And was that near to, or far away?"
"Well once, sir, he came to Curzon Street. I was upstairs, and I looked over the banisters and saw him in the hall below. I was a bit curious like, you understand, knowing the way things—er—were." Mason finished up with her discreet cough.
"And the other time?"
"I was in the Park, sir, with Annie—one of the housemaids, sir, and she pointed out the master to me walking with a foreign lady."
Again Poirot nodded.
"Now listen. Mason, this man whom you saw in the carriage talking to your mistress at the Gare de Lyon, how do you know it was not your master?"
"The master, sir? Oh, I don't think it could have been."
​"But you are not sure," Poirot persisted.
"Well—I never thought of it, sir."
Mason was clearly upset at the idea.
"You have heard that your master was also on the tram. What more natural than that it should be he who came along the corridor."
"But the gentleman who was talking to the mistress must have come from outside, sir. He was dressed for the street. In an overcoat and soft hat."
"Just so, Mademoiselle, but reflect a minute. The train has just arrived at the Gare de Lyon. Many of the passengers promenade themselves upon the quay. Your mistress was about to do so, and for that purpose had doubtless put on her fur coat, eh?"
"Yes, sir," agreed Mason.
"Your master, then, does the same. The train is heated, but outside in the station it is cold. He puts on his overcoat and his hat and he walks along beside the train, and looking up at the lighted windows he suddenly sees Madame Kettering. Until then he has had no idea that she was on the train. Naturally, he mounts the carriage and goes to her compartment. She gives an exclamation of surprise at seeing him and quickly shuts the door between the two compartments since it is possible that their conversation may be of a private nature."
He leaned back in his chair and watched the suggestion slowly take effect. No one knew better than Hercule Poirot that the class to which Mason belongs cannot be hurried. He must give her time to get rid of her own preconceived ideas. At the end of three minutes she spoke:
​"Well, of course, sir, it might be so. I never thought of it that way. The master is tall and dark, and just about that build. It was seeing the hat and coat that made me say it was a gentleman from outside. Yes, it might have been the master. I would not like to say either way, I am sure."
"Thank you very much. Mademoiselle. I shall not require you any further. Ah, just one thing more." He took from his pocket the cigarette case he had already shown to Katherine. "Is that your mistress's case?" he said to Mason.
"No, sir, it is not the mistress's—at least——"
She looked suddenly startled. An idea was clearly working its way to the forefront of her mind.
"Yes," said Poirot encouragingly.
"I think, sir—I can't be sure, but I think—it is a case that the mistress bought to give to the master."
"Ah," said Poirot in a non-committal manner.
"But whether she ever did give it to him or not, I can't say, of course."
"Precisely," said Poirot, "precisely. That is all, I think. Mademoiselle. I wish you good afternoon."
Ada Mason retired discreetly, closing the door noiselessly behind her.
Poirot looked across at Van Aldin, a faint smile upon his face. The millionaire looked thunderstruck.
"You think—you think it was Derek?" he queried, "but—everything points the other way. Why, the Count has actually been caught redhanded with the jewels on him."
"No."
"But you told me——"
​"What did I tell you?"
"That story about the jewels. You showed them to me."
"No."
Van Aldin stared at him.
"You mean to say you didn't show them to me?"
"No."
"Yesterday—at the tennis?"
"No."
"Are you crazy, M. Poirot, or am I?"
"Neither of us is crazy," said the detective. "You ask me a question; I answer it. You say have I not shown you the jewels yesterday? I reply—no. What I showed you, M. Van Aldin, was a first-class imitation, hardly to be distinguished except by an expert from the real ones."