“What do I think? I think a certain lady walked up to the front door and rang the bell, quite calm and smiling, the afternoon caller… Maybe she asked for Miss Holland, or for Miss Megan, or perhaps she had brought a parcel. Anyway Agnes turns round to get a salver for cards, or to take the parcel in, and our ladylike caller bats her on the back of her unsuspecting head.”

“What with?”

Nash said:

“The ladies round here usually carry large sizes in handbags. No saying what mightn’t be inside it.”

“And then stabs her through the back of the neck and bundles her into the cupboard? Wouldn’t that be a hefty job for a woman?”

Superintendent Nash looked at me with rather a queer expression.

“The woman we’re after isn’t normal—not by a long way—and that type of mental instability goes with surprising strength. Agnes wasn’t a big girl.”

He paused and then asked: “What made Miss Megan Hunter think of looking in that cupboard?”

“Sheer instinct,” I said.

Then I asked: “Why drag Agnes into the cupboard? What was the point?”

“The longer it was before the body was found, the more difficult it would be to fix the time of death accurately. If Miss Holland, for instance, fell over the body as soon as she came in, a doctor might be able to fix it within ten minutes or so—which might be awkward for our lady friend.”

I said, frowning:

“But if Agnes were suspicious of this person—”

Nash interrupted me.

“She wasn’t. Not to the pitch of definite suspicion. She just thought it ‘queer.’ She was a slow-witted girl, I imagine, and she was only vaguely suspicious with a feeling that something was wrong. She certainly didn’t suspect that she was up against a woman who would do murder.”

“Did you suspect that?” I asked.

Nash shook his head. He said, with feeling:

“I ought to have known. That suicide business, you see, frightened Poison Pen. She got the wind up. Fear, Mr. Burton, is an incalculable thing.”

“Yes, fear. That was the thing we ought to have foreseen. Fear—in a lunatic brain….

“You see,” said Superintendent Nash, and somehow his words made the whole thing seem absolutely horrible. “We’re up against someone who’s respected and thought highly of—someone, in fact, of good social position!”

III

Presently Nash said that he was going to interview Rose once more. I asked him, rather diffidently, if I might come too. Rather to my surprise he assented cordially.

“I’m very glad of your cooperation, Mr. Burton, if I may say so.”

“That sounds suspicious,” I said. “In books when a detective welcomes someone’s assistance, that someone is usually the murderer.”

Nash laughed shortly. He said: “You’re hardly the type to write anonymous letters, Mr. Burton.”

He added: “Frankly, you can be useful to us.”