Poirot's eyes were shining with the green light I knew so well.
"How was it called, this book?" he asked.
"The Hidden Hand in China, I think it was called."
"Aha!" said Poirot, with almost a gasp.
Then he said quickly, "Let me see the Chinaman, Ah Ling."
The Chinaman was sent for and appeared, shuffling along, with his eyes cast down, and his pigtail swinging.
His impassive face showed no trace of any kind of emotion.
"Ah Ling," said Poirot, "are you sorry your master is dead?"
"I welly sorry.
He good master."
"You know who kill him?"
"I not know.
I tell pleeceman if I know."
The questions and answers went on.
With the same impassive face. Ah Ling described how he had made the curry.
The cook had had nothing to do with it, he declared, no hand had touched it but his own.
I wondered if he saw where his admission was leading him.
He stuck to it too, that the window to the garden was bolted that evening.
If it was open in the morning, his master must have opened it himself.
At last Poirot dismissed him.
"That will do, Ah Ling." Just as the Chinaman had got to the door, Poirot recalled him. "And you know nothing, you say, of the Yellow Jasmine?"
"No, what should I know?"
"Nor yet of the sign that was written underneath it?"
Poirot leant forward as he spoke, and quickly traced something on the dust of a little table.
I was near enough to see it before he rubbed it out.
A down stroke, a line at right angles, and then a second line down which completed a big 4.
The effect on the Chinaman was electrical.
For one moment his face was a mask of terror.
Then, as suddenly, it was impassive again, and repeating his grave disclaimer, he withdrew.
Japp departed in search of young Paynter, and Poirot and I were left alone together.
"The Big Four, Hastings," cried Poirot. "Once again, the Big Four.
Paynter was a great traveller.
In his book there was doubtless some vital information concerning the doings of Number One, Li Chang Yen, the head and brains of the Big Four."
"But who - how -"
"Hush, here they come."
Gerald Paynter was an amiable, rather weak-looking young man.
He had a soft brown beard, and a peculiar flowing tie.
He answered Poirot's questions readily enough.
"I dined out with some neighbours of ours, the Wycherlys," he explained. "What time did I get home?
Oh, about eleven.
I had a latch-key, you know.
All the servants had gone to bed, and I naturally thought my uncle had done the same.
As a matter of fact, I did think I caught sight of that soft-footed Chinese beggar Ah Ling just whisking round the corner of the hall, but I fancy I was mistaken."
"When did you last see your uncle, Mr. Paynter?
I mean before you came to live with him."
"Oh! not since I was a kid of ten.
He and his brother (my father) quarrelled, you know."
"But he found you again with very little trouble, did he not?
In spite of all the years that had passed?"
"Yes, it was quite a bit of luck my seeing the lawyer's advertisement."