"A twin, "I cried.

"Exactly, Hastings. You jump to the right conclusion with unfailing accuracy. But here we are at home again.

Let us at once get to work on that little affair of the

Duchess's necklace."

But the Duchess's necklace was doomed to wait

awhile. A case of quite another description was waiting

for us.

Our landlady, Mrs. Pearson, at once informed us that

a hospital nurse had called and was waiting to see

Poirot.

We found her sitting in the big arm-chair facing the

window, a pleasant-faced woman of middle age, in a

dark blue uniform. She was a little reluctant to come to the point, but Poirot soon put her at her ease, and she

embarked upon her story.

"You see, M. Poirot, I've never come across anything of the kind before. I was sent for, from the Lark Sisterhood, to go down to a case in Hertfordshire. An old

gentleman, it is, Mr. Templeton. Quite a pleasant

house, and quite pleasant people. The wife, Mrs.

Templeton, is much younger than her husband, and he

has a son by his first marriage who lives there. I don't know that the young man and the step-mother always

get on together. He's not quite what you'd call normal

--not 'wanting' exactly, but decidedly dull in the intellect. Well, this illness of Mr. Templeton's seemed to me

from the first to be very mysterious. At times there

THE BIG FOUR 169

seemed really nothing the matter with him, and then he

suddenly has one of these gastric attacks with pain and

vomiting. But the doctor seemed quite satisfied, and it

wasn't for me to say anything. But I couldn't help

thinking about it. And then--"

She paused, and became rather red.

"Something happened which aroused your suspicions?" suggested Poirot.

"Yes."

But she still seemed to find it difficult to go on.

"I found the servants were passing remarks too."

"About Mr. Templeton's illness?"

"Oh, no! About--about this other thing--"

"Mrs. Templeton?"

"Yes."

"Mrs. Templeton and the doctor, perhaps?"

Poirot had an uncanny flair in these things. The nurse

threw him a grateful glance and went on.

"They were passing remarks. And then one day I

happened to see them together myself--in the garden--"

It was left at that. Our client was in such an agony of

outraged propriety that no one could feel it necessary to ask exactly what she had seen in the garden. She had

evidently seen quite enough to make up her own mind

on the situation.

"The attacks got worse and worse. Dr. Treves said it was all perfectly natural and to be expected, and that

Mr. Templeton could not possibly live long, but I've

never seen anything like it before myself--not in all my ong experience of nursing. It seemed to me much more

"he some form of--"

She paused, hesitating.

"Arsenical poisoning?" said Poirot helpfully. ahe nodded.

"And then, too, he, the patient, I mean, said something queer. 'They'll do for me, the four of them.