“You’re failing to allow for the mentality of a Poison Pen—all is grist that comes to their mill. Their grudge, you might say, is against humanity.”

“I suppose,” said Joanna thoughtfully, “that that is what Mrs. Dane Calthrop meant.”

Nash looked at her inquiringly, but she did not enlighten him. The superintendent said:

“I don’t know if you happened to look closely at the envelope of the letter you got, Miss Burton. If so, you may have noticed that it was actually addressed to Miss Barton, and the a altered to a u afterwards.”

That remark, properly interpreted, ought to have given us a clue to the whole business. As it was, none of us saw any significance in it.

Nash went off, and I was left with Joanna. She actually said: “You don’t think that letter can really have been meant for Miss Emily, do you?”

“It would hardly have begun ‘You painted trollop,’” I pointed out, and Joanna agreed.

Then she suggested that I should go down to the town. “You ought to hear what everyone is saying. It will be the topic this morning!”

I suggested that she should come too, but rather to my surprise Joanna refused. She said she was going to mess about in the garden.

I paused in the doorway and said, lowering my voice:

“I suppose Partridge is all right?”

“Partridge!”

The amazement in Joanna’s voice made me feel ashamed of my idea. I said apologetically: “I just wondered. She’s rather ‘queer’ in some ways—a grim spinster—the sort of person who might have religious mania.”

“This isn’t religious mania—or so you told me Graves said.”

“Well, sex mania. They’re very closely tied up together, I understand. She’s repressed and respectable, and has been shut up here with a lot of elderly women for years.”

“What put the idea into your head?”

I said slowly:

“Well, we’ve only her word for it, haven’t we, as to what the girl Agnes said to her? Suppose Agnes asked Partridge to tell her why Partridge came and left a note that day—and Partridge said she’d call round that afternoon and explain.”

“And then camouflaged it by coming to us and asking if the girl could come here?”

“Yes.”

“But Partridge never went out that afternoon.”

“We don’t know that. We were out ourselves, remember.”

“Yes, that’s true. It’s possible, I suppose.” Joanna turned it over in her mind. “But I don’t think so, all the same. I don’t think Partridge has the mentality to cover her tracks over the letters. To wipe off fingerprints, and all that. It isn’t only cunning you want—it’s knowledge. I don’t think she’s got that. I suppose—” Joanna hesitated, then said slowly, “they are sure it is a woman, aren’t they?”

“You don’t think it’s a man?” I exclaimed incredulously.

“Not—not an ordinary man—but a certain kind of man. I’m thinking, really, of Mr. Pye.”

“So Pye is your selection?”

“Don’t you feel yourself that he’s a possibility? He’s the sort of person who might be lonely—and unhappy—and spiteful. Everyone, you see, rather laughs at him. Can’t you see him secretly hating all the normal happy people, and taking a queer perverse artistic pleasure in what he was doing?”