It is an insult what you say there!"
Poirot shook his head gently, but made no answer.
Desjardeaux looked at him in stupefaction for some moments.
Then his face cleared, and he glanced at the Home Secretary and tapped his forehead significantly.
"M. Poirot is a great man," he observed. "But even the great man - sometimes he has his little mania, does he not?
And seeks in high places for fancied conspiracies.
It is well known.
You agree with me, do you not, Mr. Crowther?"
The Home Secretary did not answer for some minutes.
Then he spoke slowly and heavily.
"Upon my soul, I don't know," he said at last. "I have always had and still have the utmost belief in M. Poirot, but - well, this takes a bit of believing."
"This Li Chang Yen, too," continued M. Desjardeaux. "Who has ever heard of him?"
"I have," said the unexpected voice of Mr. Ingles.
The Frenchman stared at him, and he stared placidly back again, looking more like a Chinese idol than ever.
"Mr. Ingles," explained the Home Secretary, "is the greatest authority we have on the interior of China."
"And you have heard of this Li Chang Yen?"
"Until M. Poirot here came to me, I imagined that I was the only man in England who had.
Make no mistake, M. Desjardeaux, there is only one man in China who counts today - Li Chang Yen.
He has, perhaps, I only say perhaps, the finest brain in the world at the present time."
M. Desjardeaux sat as though stunned.
Presently, however, he rallied.
"There may be something in what you say, M. Poirot," he said coldly. "But as regards Madame Olivier, you are most certainly mistaken.
She is a true daughter of France, and devoted solely to the cause of science."
Poirot shrugged his shoulders and did not answer.
There was a minute or two's pause, and then my little friend rose to his feet, with an air of dignity that sat rather oddly upon his quaint personality.
"That is all I have to say, messieurs - to warn you.
I thought it likely that I should not be believed.
But at least you will be on your guard.
My words will sink in, and each fresh event that comes along will confirm your wavering faith.
It was necessary for me to speak now - later I might not have been able to do so."
"You mean -?" asked Crowther, impressed in spite of himself by the gravity of Poirot's tone.
"I mean, monsieur, that since I have penetrated the identity of Number Four, my life is not worth an hour's purchase.
He will seek to destroy me at all costs - and not for nothing is he named 'The Destroyer.'
Messieurs, I salute you.
To you, M. Crowther, I deliver this key, and this sealed envelope.
I have got together all my notes on the case, and my ideas as to how best to meet the menace that any day may break upon the world, and have placed them in a certain safe deposit.
In the event of my death, M. Crowther, I authorise you to take charge of those papers and make what use you can of them.
And now, messieurs, I wish you good day."
Desjardeaux merely bowed coldly, but Crowther sprang up and held out his hand.
"You have converted me, M. Poirot.
Fantastic as the whole thing seems, I believe utterly in the truth of what you have told us."
Ingles left at the same time as we did.
"I am not disappointed with the interview," said Poirot, as we walked along. "I did not expect to convince Desjardeaux, but I have at least ensured that, if I die, my knowledge does not die with me.
And I have made one or two converts.
Pas si mal!"
"I'm with you, as you know," said Ingles. "By the way, I'm going out to China as soon as I can get off."
"Is that wise?"
"No," said Ingles dryly. "But it's necessary.
One must do what one can."
"Ah, you are a brave man!" cried Poirot with emotion. "If we were not in the street, I would embrace you."