orp's death lay at her door. She
is seized with panic, and under its influence she hurries downstairs,
and quickly drops the coffee-cup and saucer used by Mademoiselle Cynthia
into a large brass vase, where it is discovered later by Monsieur
Lawrence. The remains of the coco she dare not touch. Too many eyes
are upon her. Guess at her relief when strychnine is mentioned, and she
discovers that after all the tragedy is not her doing.

"We are now able to account for the symptoms of strychnine poisoning
being so long in making their appearance. A narcotic taken with
strychnine will delay the action of the poison for some hours."

Poirot paused. Mary looked up at him, the colour slowly rising in her
face.

"All you have said is quite true, Monsieur Poirot. It was the most
awful hour of my life. I shall never forget it. But you are wonderful. I
understand now----"

"What I meant when I told you that you could safely confess to Papa
Poirot, eh? But you would not trust me."

"I see everything now," said Lawrence. "The drugged coco, taken on top
of the poisoned coffee, amply accounts for the delay."

"Exactly. But was the coffee poisoned, or was it not? We come to a
little difficulty here, since Mrs. Inglethorp never drank it."

"What?" The cry of surprise was universal.

"No. You will remember my speaking of a stain on the carpet in Mrs.
Inglethorp's room? There were some peculiar points about that stain. It
was still damp, it exhaled a strong odour of coffee, and imbedded in
the nap of the carpet I found some little splinters of china. What had
happened was plain to me, for not two minutes before I had placed my
little case on the table near the window, and the table, tilting up, had
deposited it upon the floor on precisely the identical spot. In exactly
the same way, Mrs. Inglethorp had laid down her cup of coffee on
reaching her room the night before, and the treacherous table had played
her the same trick.

"What happened next is mere guess work on my part, but I should say that
Mrs. Inglethorp picked up the broken cup and placed it on the table by
the bed. Feeling in need of a stimulant of some kind, she heated up
her coco, and drank it off then and there. Now we are faced with a new
problem. We know the coco contained no strychnine. The coffee was never
drunk. Yet the strychnine must have been administered between seven
and nine o'clock that evening. What third medium was there--a medium so
suitable for disgu