“ ‘Find the extra coffee-cup, and you can rest in peace.’ Is that right?” I asked, much mystified.
“Excellent.”
“But what does it mean?”
“Ah, that I will leave you to find out. You have access to the facts. Just say that to him, and see what he says.”
“Very well—but it’s all extremely mysterious.”
We were running into Tadminster now, and Poirot directed the car to the “Analytical Chemist.”
Poirot hopped down briskly, and went inside. In a few minutes he was back again.
“There,” he said. “That is all my business.”
“What were you doing there?” I asked, in lively curiosity.
“I left something to be analysed.”
“Yes, but what?”
“The sample of cocoa I took from the saucepan in the bedroom.”
“But that has already been tested!” I cried, stupefied. “ Dr. Bauerstein had it tested, and you yourself laughed at the possibility of there being strychnine in it.”
“I know Dr. Bauerstein had it tested,” replied Poirot quietly.
“Well, then?”
“Well, I have a fancy for having it analysed again, that is all.”