What then was the sequence of events?
Raymond Boynton returns to the camp, sees his mother sitting at the mouth of her cave, goes up to her and finds she is dead.
What does he do?
Does he call for help?
Does he immediately inform the camp of what has happened?
No, he waits a minute or two, then passes on to his tent and joins his family in the marquee and says nothing.
Such conduct is exceedingly curious, is it not?"
Raymond said, in a nervous sharp voice: "It would be idiotic, of course. That ought to show you that my mother was alive and well, as I've said.
Miss King was flustered and upset and made a mistake."
"One asks oneself," said Poirot, calmly sweeping on, whether there could possibly be a reason for such conduct?
It seems, on the face of it, that Raymond Boynton cannot be guilty, since at the only time he was known to approach his stepmother that afternoon, she had already been dead for some time.
Now, supposing, therefore, that Raymond Boynton is innocent, can we explain his conduct?" "And I say, that on the assumption that he is innocent we can!
For I remember that fragment of conversation I overheard.
'You do see, don't you, that she's got to be killed?'
He comes back from his walk and finds her dead and at once his guilty memory envisages a certain possibility.
The plan has been carried out, not by him, but by his fellow planner.
Tout simplement he suspects that his sister, Carol Boynton, is guilty."
"It's a lie," said Raymond in a low, trembling voice.
Poirot went on: "Let us now take the possibility of Carol Boynton being the murderess.
What is the evidence against her?
She has the same highly-strung temperament - the kind of temperament that might see such a deed colored with heroism.
It was she to whom Raymond Boynton was talking that night in Jerusalem.
Carol Boynton returned to the camp at ten minutes past five.
According to her own story, she went up and spoke to her mother.
No one saw her do so.
The camp was deserted - the boys were asleep.
Lady Westholme, Miss Pierce and M. Cope were exploring caves out of sight of the camp. There was no witness to Carol Boynton's possible action.
The time would agree well enough. The case, then, against Carol Boynton, is a perfectly possible one."
He paused.
Carol had raised her head. Her eyes looked steadily and sorrowfully into his.
"There is one other point.
The following morning, very early, Carol Boynton was seen to throw something into the stream.
There is reason to believe that that 'something' was a hypodermic syringe."
"Comment?" Dr. Gerard looked up surprised. "But my hypodermic was returned.
Yes, yes, I have it now."
Poirot nodded vigorously.
"Yes, yes.
This second hypodermic, it is very curious - very interesting.
I have been given to understand that this hypodermic belonged to Miss King.
Is that so?"
Sarah paused for a fraction of a second.
Carol spoke quickly: "It was not Miss King's syringe," she said. "It was mine."
"Then you admit throwing it away, Mademoiselle?"
She hesitated just a second. "Yes, of course. Why shouldn't I?"
"Carol!" It was Nadine. She leaned forward, her eyes wide and distressed. "Carol. . . Oh, I don't understand..."
Carol turned and looked at her.
There was something hostile in her glance.
"There's nothing to understand!
I threw away an old hypodermic. I never touched the - the poison." Sarah's voice broke in.
"It is quite true what Miss Pierce told you, M. Poirot. It was my syringe."