1"You have changed, Mademoiselle," said Poirot suddenly. He and Katherine were seated opposite each other at a small table at the Savoy.

2"Yes, you have changed," he continued.

3"In what way?"

4"Mademoiselle, these nuances are difficult to express."

5"I am older."

6"Yes, you are older. And by that I do not mean that the wrinkles and the crows' feet are coming. When I first saw you, Mademoiselle, you were a looker-on at life. You had the quiet, amused look of one who sits back in the stalls and watches the play."

7"And now?"

8"Now, you no longer watch. It is an absurd thing, perhaps, that I say here, but you have the wary look of a fighter who is playing a difficult game."

9"My old lady is difficult sometimes," said Katherine, with a smile; "but I can assure you that I don't engage in deadly contests with her. You must go down and see her some day, Monsieur Poirot. I think you are one of the people who would appreciate her pluck and her spirit."

10There was a silence while the waiter deftly served them with chicken en casserole. When he had departed, Poirot said:

11"You have heard me speak of my friend Hastings?—he who said that I was a human oyster. Eh bien, Mademoiselle, I have met my match in you. You, far more than I, play a lone hand."

12"Nonsense," said Katherine lightly.

13"Never does Hercule Poirot talk nonsense. It is as I say."

14Again there was a silence. Poirot broke it by inquiring:

15"Have you seen any of our Riviera friends since you have been back, Mademoiselle?"

16"I have seen something of Major Knighton."

17"A-ha! Is that so?"

18Something in Poirot's twinkling eyes made Katherine lower hers.

19"So Mr. Van Aldin remains in London?"

20"Yes."

21"I must try to see him to-morrow or the next day."

22"You have news for him?"

23"What makes you think that?"

24"I—wondered, that is all."

25Poirot looked across at her with twinkling eyes.

26"And now, Mademoiselle, there is much that you wish to ask me, I can see that. And why not? Is not the affair of the Blue Train our own 'Roman Policier'?"

27"Yes, there are things I should like to ask you."

28"Eh bien?"

29Katherine looked up with a sudden air of resolution.

30"What were you doing in Paris, Monsieur Poirot?"

31Poirot smiled slightly.

32"I made a call at the Russian Embassy."

33"Oh."

34"I see that that tells you nothing. But I will not be a human oyster. No, I will lay my cards on the table, which is assuredly a thing that oysters do not do. You suspect, do you not, that I am not satisfied with the case against Derek Kettering?"

35"That is what I have been wondering. I thought, in Nice, that you had finished with the case."

36"You do not say all that you mean, Mademoiselle. But I admit everything. It was I—my researches—which placed Derek Kettering where he is now. But for me the Examining Magistrate would still be vainly trying to fasten the crime on the Comte de la Roche. Eh bien, Mademoiselle, what I have done I do not regret. I have only one duty—to discover the truth, and that way led straight to Mr. Kettering. But did it end there? The police say yes, but I, Hercule Poirot, am not satisfied."

37He broke off suddenly. "Tell me, Mademoiselle, have you heard from Mademoiselle Lenox lately?"

38"One very short, scrappy letter. She is, I think, annoyed with me for coming back to England."

39Poirot nodded.

40"I had an interview with her the night that Monsieur Kettering was arrested. It was an interesting interview in more ways than one."

41Again he fell silent, and Katherine did not interrupt his train of thought.

42"Mademoiselle," he said at last, "I am now on delicate ground, yet I will say this to you. There is, I think, some one who loves Monsieur Kettering—correct me if I am wrong—and for her sake—well—for her sake I hope that I am right and the police are wrong. You know who that some one is?"

43There was a pause, then Katherine said:

44"Yes—I think I know."

45Poirot leant across the table towards her.

46"I am not satisfied, Mademoiselle; no, I am not satisfied. The facts, the main facts, led straight to Monsieur Kettering. But there is one thing that has been left out of account."

47"And what is that?"

48"The disfigured face of the victim. I have asked myself, Mademoiselle, a hundred times, 'Was Derek Kettering the kind of man who would deal that smashing blow after having committed the murder?' What end would it serve? What purpose would it accomplish? Was it a likely action for one of Monsieur Kettering's temperament? And, Mademoiselle, the answer to these questions is profoundly unsatisfactory. Again and again I go back to that one point—'why?' And the only things I have to help me to a solution of the problem are these."

49He whipped out his pocket-book and extracted something from it which he held between his finger and thumb.

50"Do you remember, Mademoiselle? You saw me take these hairs from the rug in the railway carriage."

51Katherine leant forward, scrutinizing the hairs keenly.

52Poirot nodded his head slowly several times.

53"They suggest nothing to you, I see that, Mademoiselle. And yet—I think somehow that you see a good deal."

54"I have had ideas," said Katherine slowly, "curious ideas. That is why I ask you what you were doing in Paris, Monsieur Poirot."

55"When I wrote to you—"

56"From the Ritz?"

57A curious smile came over Poirot's face.

58"Yes, as you say, from the Ritz. I am a luxurious person sometimes—when a millionaire pays."

59"The Russian Embassy," said Katherine, frowning. "No, I don't see where that comes in."

60"It does not come in directly, Mademoiselle. I went there to get certain information. I saw a particular personage and I threatened him—yes, Mademoiselle, I, Hercule Poirot, threatened him."

61"With the police?"

62"No," said Poirot drily, "with the Press—a much more deadly weapon."

63He looked at Katherine and she smiled at him, just shaking her head.

64"Are you not just turning back into an oyster again, Monsieur Poirot?"

65"No, no! I do not wish to make mysteries. See, I will tell you everything. I suspect this man of being the active party in the sale of the jewels of Monsieur Van Aldin. I tax him with it, and in the end I get the whole story out of him. I learn where the jewels were handed over, and I learn, too, of the man who paced up and down outside in the street—a man with a venerable head of white hair, but who walked with the light, springy step of a young man—and I give that man a name in my own mind—the name of 'Monsieur le Marquis.'"

66"And now you have come to London to see Mr. Van Aldin?"

67"Not entirely for that reason. I had other work to do. Since I have been in London I have seen two more people—a theatrical agent and a Harley Street doctor. From each of them I have got certain information. Put these things together, Mademoiselle, and see if you can make of them the same as I do."

68"I?"

69"Yes, you. I will tell you one thing, Mademoiselle. There has been a doubt all along in my mind as to whether the robbery and the murder were done by the same person. For a long time I was not sure—"

70"And now?"

71"And now I know."

72There was a silence. Then Katherine lifted her head. Her eyes were shining.

73"I am not clever like you, Monsieur Poirot. Half the things that you have been telling me don't seem to me to point anywhere at all. The ideas that came to me came from such an entirely different angle—"

74"Ah, but that is always so," said Poirot quietly. "A mirror shows the truth, but every one stands in a different place for looking into the mirror."

75"My ideas may be absurd—they may be entirely different from yours, but—"

76"Yes?"

77"Tell me, does this help you at all?"

78He took a newspaper cutting from her outstretched hand. He read it and, looking up, he nodded gravely.

79"As I told you, Mademoiselle, one stands at a different angle for looking into the mirror, but it is the same mirror and the same things are reflected there."

80Katherine got up. "I must rush," she said. "I have only just time to catch my train. Monsieur Poirot—"

81"Yes, Mademoiselle."

82"It—it mustn't be much longer, you understand. I—I can't go on much longer."

83There was a break in her voice.

84He patted her hand reassuringly.

85"Courage, Mademoiselle, you must not fail now; the end is very near."