I decided to believe Ah Ling -"
"What?" I exclaimed.
"You are surprised, Hastings?
Ah Ling knew of the existence of the Big Four, that was evident - so evident that it was clear he knew nothing of their association with the crime until that moment.
Had he been the murderer, he would have been able to retain his impassive face perfectly.
So I decided then, to believe Ah Ling, and I fixed my suspicions on Gerald Paynter.
It seemed to me that Number Four would have found an impersonation of a long lost nephew very easy."
"What!" I cried. "Number Four?"
"No, Hastings, not Number Four.
As soon as I had read up the subject of yellow jasmine, I saw the truth.
In fact, it leapt to the eye."
"As always," I said coldly, "it doesn't leap to mine."
"Because you will not use your little gray cells.
Who had a chance to tamper with the curry?"
"Ah Ling.
No one else."
"No one else?
What about the doctor?"
"But that was afterwards."
"Of course it was afterwards.
There was no trace of powdered opium in the curry served to Mr. Paynter, but acting in obedience to the suspicions Dr. Quentin had aroused, the old man eats none of it, and preserves it to give to his medical attendant, whom he summons according to plan.
Dr. Quentin arrives, takes charge of the curry, and gives Mr. Paynter an injection - of strychnine, he says, but really of yellow jasmine - a poisonous dose.
When the drug begins to take effect, he departs, after unlatching the window.
Then, in the night, he returns by the window, finds the manuscript, and shoves Mr. Paynter into the fire.
He does not heed the newspaper that drops to the floor and is covered by the old man's body.
Paynter knew what drug he had been given, and strove to accuse the Big Four of his murder.
It is easy for Quentin to mix powdered opium with the curry before handing it over to be analysed.
He gives his version of the conversation with the old man, and mentions the strychnine injection casually, in case the mark of the hypodermic needle is noticed.
Suspicion at once is divided between accident and the guilt of Ah Ling owing to the poison in the curry."
"But Dr. Quentin cannot be Number Four?"
"I fancy he can.
There is undoubtedly a real Dr. Quentin who is probably abroad somewhere.
Number Four has simply masqueraded as him for a short time.
The arrangements with Dr. Bolitho were all carried out by correspondence, the man who was to do locum originally having been taken ill at the last minute."
At that minute, Japp burst in, very red in the face.
"You have got him?" cried Poirot anxiously.
Japp shook his head, very out of breath.
"Bolitho came back from his holiday this morning - recalled by telegram.
No one knows who sent it.
The other man left last night.
We'll catch him yet, though."
Poirot shook his head quietly.
"I think not," he said, and absent-mindedly he drew a big 4 on the table with a fork.
Chapter 11 A CHESS PROBLEM
Poirot and I often dined at a small restaurant in Soho.
We were there one evening, when we observed a friend at an adjacent table.
It was Inspector Japp, and as there was room at our table, he came and joined us.
It was some time since either of us had seen him.
"Never do you drop in to see us nowadays," declared Poirot reproachfully. "Not since the affair of the Yellow Jasmine have we met, and that is nearly a month ago."
"I've been up north - that's why.