They'11 do for me yet.' "

"Eh?" said Poirot quickly.

"Those were his very words, M. Poirot. He was in

great pain at the time, of course, and hardly knew what

he was saying."

" 'They'll do for me, the four of them,' " repeated Poirot thoughtfully. "What did he mean by 'the four of them,'do you think?"

"That I can't say, M. Poirot. I thought perhaps he

meant his wife and son, and the doctor, and perhaps

Miss dark, Mrs. Templeton's companion. That would

make four, wouldn't it? He might think they were all in

league against him."

"Quite so, quite so," said Poirot, in a preoccupied voice. "What about food? Could you take no precautions about that?"

"I'm always doing what I can. But, of course, sometimes Mrs. Templeton insists on bringing him his food

herself, and then there are the times when I am off

duty."

"Exactly. And you are not sure enough of your

ground to go to the police?"

The nurse's face showed her horror at the mere idea.

"What I have done, M. Poirot, is this. Mr. Templeton had a very bad attack after partaking of a bowl of

soup. I took a little from the bottom of the bowl afterwards, and have brought it up with me. I have been

spared for the day to visit a sick mother, as Mr. Templeton was well enough to be left."

She drew out a little bottle of dark fluid and handed it to Poirot.

"Excellent, mademoiselle. We will have this analysed immediately. If you will return here in, say, an hour's

THE BIG FOUR 171

time I think that we shall be able to dispose of your

suspicions one way or another."

First extracting from our visitor her name and qualifications, he ushered her out. Then he wrote a note and

sent it off together with the bottle of soup. Whilst we

waited to hear the result, Poirot amused himself by verifying the nurse's credentials, somewhat to my surprise.

"No, no, my friend," he declared. "I do well to be careful. Do not forget the Big Four are on our track." However, he soon elicited the information that a

nurse of the name of Mabel Palmer was a member of

the Lark Institute and had been sent to the case in question.

"So far, so good," he said, with a twinkle. "And now here comes Nurse Palmer back again, and here also

is our analyst's report."

Both the nurse and I waited anxiously whilst Poirot

read the analyst's report.

"Is there arsenic in it?" she asked breathlessly. Poirot shook his head, refolding the paper.

"No."

We were both immeasurably surprised.

"There is no arsenic in it," continued Poirot. "But there is antimony. And that being the case, we will start immediately for Hertfordshire. Pray Heaven that we are

not too late."

It was decided that the simplest plan was for Poirot to

represent himself truly as a detective, but that the ostensible reason of his visit should be to question Mrs.