"I will tell you, M. Poirot. You have heard of this dancer woman—Mirelle?"
"She who is the chère amie of M. Derek Kettering?"
"Yes, that is the one; and, knowing this, you will understand that Mr. Van Aldin is naturally prejudiced against her. She wrote to him, asking for an interview. He told me to dictate a curt refusal, which of course I did. This morning she came to the hotel and sent up her card, saying that it was urgent and vital that she should see Mr. Van Aldin at once."
"You interest me," said Poirot.
"Mr. Van Aldin was furious. He told me what message to send down to her. I ventured to disagree with him. It seemed to me both likely and probable that this woman Mirelle might give us valuable information. We know that she was on the Blue Train, and she may have seen or heard something that it might be vital for us to know. Don't you agree with me, M. Poirot?"
"I do," said Poirot drily. "M. Van Aldin, if I may say so, behaved exceedingly foolishly."
"I am glad you take that view of the matter," said the secretary. "Now I am going to tell you something, M. Poirot. So strongly did I feel the unwisdom of Mr. Van Aldin's attitude that I went down privately and had an interview with the lady."
"Eh bien?"
"The difficulty was that she insisted on seeing Mr. Van Aldin himself. I softened his message as much as I possibly could. In fact—to be candid—I gave it in a very different form. I said that Mr. Van Aldin was too busy to see her at present, but that she might make any communication she wished to me. That, however, she could not bring herself to do, and she left without saying anything further. But I have a strong impression, M. Poirot, that that woman knows something."
"This is serious," said Poirot quietly. "You know where she is staying?"