I went home with a feeling of exultation. My scheme had succeeded far better than I could possibly have hoped. Lord Nasby had been positively genial. It only now remained for me to “Make good,” as he expressed it. Once locked in my own room, I took out my precious piece of paper and studied it attentively. Here was the clue to the mystery. 

To begin with, what did the figures represent? There were five of them, and a dot after the first two. “Seventeen—one hundred and twenty-two,” I murmured.

That did not seem to lead to anything.

Next I added them up. That is often done in works of fiction and leads to surprising deductions.

“One and seven make eight and one is nine and two are eleven and two are thirteen.”

Thirteen! Fateful number! Was this a warning to me to leave the whole thing alone? Very possibly. Anyway, except as a warning, it seemed to be singularly useless. I declined to believe that any conspirator would take that way of writing thirteen in real life. If he meant thirteen, he would write thirteen. “13”—like that.

There was a space between the one and the two. I accordingly subtracted twenty-two from a hundred and seventy-one. The result was a hundred and fifty-nine. I did it again and made it a hundred and forty-nine. These arithmetical exercises were doubtless excellent practice, but as regarded the solution of the mystery, they seemed totally ineffectual. I left arithmetic alone, not attempting fancy division or multiplication, and went on to the words.

Kilmorden Castle. That was something definite. A place. Probably the cradle of an aristocratic family. (Missing heir? Claimant to title?) Or possibly a picturesque ruin. (Buried treasure?)

Yes, on the whole I inclined to the theory of buried treasure. Figures always go with buried treasure. One pace to the right, seven paces to the left, dig one foot, descend twenty-two steps. That sort of idea. I could work out that later. The thing was to get to Kilmorden Castle as quickly as possible.

I made a strategic sally from my room and returned laden with books of reference. Who’s Who, Whitaker, a Gazetteer, a History of Scotch Ancestral Homes, and Somebody or other’s British Isles.

Time passed. I searched diligently, but with growing annoyance. Finally, I shut the last book with a bang. There appeared to be no such place as Kilmorden Castle. Here was an unexpected check. There must be such a place. Why should any one invent a name like that and write it down on a piece of paper? Absurd!

Another idea occurred to me. Possibly it was a castellated abomination in the suburbs with a high-sounding name invented by its owner. But if so, it was going to be extraordinarily hard to find. I sat back gloomily on my heels (I always sit on the floor to do anything really important) and wondered how on earth I was to set about it.

Was there any other line I could follow? I reflected earnestly and then sprang to my feet delightedly. Of course! I must visit the “scene of the crime.” Always done by the best sleuths! And no matter how long afterwards it may be, they always find something that the police have overlooked. My course was clear. I must go to Marlow.

But how was I to get into the house? I discarded several adventurous methods, and plumped for stern simplicity. The house had been to let—presumably was still to let. I would be a prospective tenant.

I also decided on attacking the local house-agents, as having fewer houses on their books.

Here, however, I reckoned without my host. A pleasant clerk produced particulars of about half a dozen desirable properties. It took all my ingenuity to find objections to them. In the end I feared I had drawn a blank.

“And you’ve really nothing else?” I asked, gazing pathetically into the clerk’s eyes. “Something right on the river, and with a fair amount of garden and a small lodge,” I added, summing up the main points of the Mill House, as I had gathered them from the papers.

“Well, of course there’s Sir Eustace Pedler’s place,” said the man doubtfully. “The Mill House, you know.”

“Not—not where——” I faltered. (Really, faltering is getting to be my strong point.)

“That’s it! Where the murder took place. But perhaps you wouldn’t like——”

“Oh, I don’t think I should mind,” I said with an appearance of rallying. I felt my bona fides was now quite established. “And perhaps I might get it cheap—in the circumstances.”

A master touch that, I thought.

“Well, it’s possible. There’s no pretending that it will be easy to let now—servants and all that, you know. If you like the place after you’ve seen it, I should advise you to make an offer. Shall I write you out an order?”

“If you please.”

A quarter of an hour later I was at the lodge of the Mill House. In answer to my knock, the door flew open and a tall middle-aged woman literally bounced out.

“Nobody can go into the house, do you hear that? Fairly sick of you reporters, I am. Sir Eustace’s orders are——”

“I understood the house was to let,” I said freezingly, holding out my order. “Of course, if it’s already taken——”

“Oh, I’m sure I beg your pardon, miss. I’ve been fairly pestered with these newspaper people. Not a minute’s peace. No, the house isn’t let—nor likely to be now.”

“Are the drains wrong?” I asked in an anxious whisper.

“Oh, Lord, miss, the drains is all right! But surely you’ve heard about that foreign lady as was done to death here?”

“I believe I did read something about it in the papers,” I said carelessly.

My indifference piqued the good woman. If I had betrayed any interest, she would probably have closed up like an oyster. As it was, she positively bridled.

“I should say you did, miss! It’s been in all the newspapers. The Daily Budget’s out still to catch the man who did it. It seems, according to them, as our police are no good at all. Well, I hope they’ll get him—although a nice-looking young fellow he was and no mistake. A kind of soldierly look about him—ah, well, I dare say he’d been wounded in the war, and sometimes they go a bit queer afterwards, my sister’s boy did. Perhaps she’d used him bad—they’re a bad lot, those foreigners. Though she was a fine-looking woman. Stood there where you’re standing now.”

“Was she dark or fair?” I ventured. “You can’t tell from these newspaper portraits.”

“Dark hair, and a very white face—too white for nature, I thought, and her lips reddened something cruel. I don’t like to see it—a little powder now and then is quite another thing.”

We were conversing like old friends now. I put another question.

“Did she seem nervous or upset at all?”

“Not a bit. She was smiling to herself, quiet like, as though she was amused at something. That’s why you could have knocked me down with a feather when, the next afternoon, those people came running out calling for the police and saying there’d been murder done. I shall never get over it, and as for setting foot in that house after dark I wouldn’t do it, not if it was ever so. Why, I wouldn’t even stay here at the lodge, if Sir Eustace hadn’t been down on his bended knees to me.”

“I thought Sir Eustace Pedler was at Cannes?”

“So he was, miss. He come back to England when he heard the news, and, as to the bended knees, that was a figure of speech, his secretary, Mr. Pagett, having offered us double pay to stay on, and, as my John says, money is money nowadays.”

I concurred heartily with John’s by no means original remarks.

“The young man now,” said Mrs. James, reverting suddenly to a former point in the conversation. “He was upset. His eyes, light eyes, they were, I noticed them particular, was all shining. Excited, I thought. But I never dreamt of anything being wrong. Not even when he came out again looking all queer.”

“How long was he in the house?”

“Oh, not long, a matter of five minutes maybe.”

“How tall was he, do you think? About six foot?”

“I should say so maybe.”

“He was clean-shaven, you say?”

“Yes, miss—not even one of these toothbrush moustaches.”

“Was his chin at all shiny?” I asked on a sudden impulse.

Mrs. James stared at me with awe.

“Well, now you come to mention it, miss, it was. However did you know?”

“It’s a curious thing, but murderers often have shiny chins,” I explained wildly.

Mrs. James accepted the statement in all good faith.

“Really, now, miss. I never heard that before.”

“You didn’t notice what kind of a head he had, I suppose?”

“Just the ordinary kind, miss. I’ll fetch you the keys, shall I?”

I accepted them, and went on my way to the Mill House. My reconstructions so far I considered good. All along I had realized that the differences between the man Mrs. James had described and my Tube “doctor” were those of non-essentials. An overcoat, a beard, gold-rimmed eyeglasses. The “doctor” had appeared middle-aged, but I remembered that he had stooped over the body like a comparatively young man. There had been a suppleness which told of young joints.

The victim of the accident (the Moth Ball man, as I called him to myself) and the foreign woman, Mrs. de Castina, or whatever her real name was, had had an assignation to meet at the Mill House. That was how I pieced the thing together. Either because they feared they were being watched or for some other reason, they chose the rather ingenious method of both getting an order to view the same house. Thus their meeting there might have the appearance of pure chance.

That the Moth Ball man had suddenly caught sight of the “doctor,” and that the meeting was totally unexpected and alarming to him, was another fact of which I was fairly sure. What had happened next? The “doctor” had removed his disguise and followed the woman to Marlow. But it was possible that had he removed it rather hastily traces of spirit-gum might still linger on his chin. Hence my question to Mrs. James.

Whilst occupied with my thoughts I had arrived at the low old-fashioned door of the Mill House. Unlocking it with the key, I passed inside. The hall was low and dark, the place smelt forlorn and mildewy. In spite of myself, I shivered. Did the woman who had come here “smiling to herself” a few days ago feel no chill of premonition as she entered this house? I wondered. Did the smile fade from her lips, and did a nameless dread close round her heart? Or had she gone upstairs, smiling still, unconscious of the doom that was so soon to overtake her? My heart beat a little faster. Was the house really empty? Was doom waiting for me in it also? For the first time, I understood the meaning of the much-used word, “atmosphere.” There was an atmosphere in this house, an atmosphere of cruelty, of menace, of evil.