This brought us straight to the question which I had been waiting for the French Premier to ask.
"You say that the third member of this organisation is a Frenchwoman. Have you any idea of her name?"
"It is a well-known name, monsieur. An honoured name. Number Three is no less than the famous Madame Olivier."
At the mention of the world-famous scientist, successor to the Curies, M. Desjardeaux positively bounded from his chair, his face purple with emotion.
"Madame Olivier! Impossible! Absurd! 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."