I met the inspector just coming from the door which led into the kitchen quarters.

"How's the young lady, doctor?"

"Coming round nicely. Her mother's with her."

"I'm afraid not," I said regretfully. "It was a dark night, you. see, and the fellow had his coat collar well pulled up and his hat squashed down over his eyes."

"H'm," said the inspector. "Looked as though he wanted to conceal his face. Sure it was no one you know?"

"That's good. I've been questioning the servants. They all declare that no one has been to the back door tonight. Your description of that stranger was rather vague. Can't you give us something more definite to go upon?"

I agreed, but it occurred to me that the roughness had been of an almost exaggerated quality. If, as the inspector thought, the man had wished to hide his face, he might equally well have tried to disguise his voice.

I replied in the negative, but not as decidedly as I might have done. I remembered my impression that the stranger's voice was not unfamiliar to me. I explained this rather haltingly to the inspector.

"It was a rough, uneducated voice, you say?"

"Do you mind coming into the study with me again, doctor? There are one or two things I want to ask you."

Davis nodded. "Nothing more likely. You see, I've been instituting a few inquiries as to what Parker has been doing with himself this evening. To tell the truth, I didn't like his manner. The man knows something. When I began to question him, he got the wind up, and plumped out some garbled story of blackmail."

I acquiesced. Inspector Davis unlocked the door of the lobby, we passed through, and he locked the door again behind him.

"We don't want to be disturbed," he said grimly. "And we don't want any eavesdropping either. What's all this about blackmail?"

"If Parker heard anything about blackmail," I said slowly, "he must have been listening outside this door with his ear glued against the keyhole."

"Blackmail!" I exclaimed, very much startled.

"I'm rather glad you've brought the matter up," I said. "I've been trying to decide whether to make a clean breast of things or not. I'd already practically decided to tell you everything, but I was going to wait for a favourable opportunity. You might as well have it now." And then and there I narrated the whole events of the evening as I have set them down here. The inspector listened keenly, occasionally interjecting a question.

"Is it an effort of Parker's imagination? Or is there something in it?"

I took an instant decision.

I nodded. "I realize that."

"You say that Mr Ackroyd hinted at a suspicion he had that some member of his household was involved? Household's rather an elastic term."

"There's only one thing against it," I said slowly. "If Ackroyd went on reading that letter as soon as I left, as he intended to do. don't see him continuing to sit on here and tum things over in his mind for another hour. He'd have had Parker in at once, accused him then and there, and there would have been a fine old uproar. Remember, Ackroyd was a man of choleric temper."

"It looks very like it. He was obviously listening at the door when you came out. Then Miss Ackroyd came across him later bent on entering the study. Say he tried again when she was safely out of the way. He stabbed Ackroyd, locked the door on the inside, opened the window, and got out that way, and went round to a side door which he had previously left open. How's that?"

"You don't think that Parker himself might be the man we're after?" I suggested.

"Most extraordinary story I ever heard," he said, when I had finished. "And you say that letter has completely disappeared? It looks bad -- it looks very bad indeed. It gives us what we've been looking for -- a motive for the murder."

"And the telephone call?

"Parker sent that all right -- perhaps before he thought of the locked door and open window. Then he changed his mind -- or got in a panic -- and decided to deny all knowledge of it. That was it, depend upon it."

"Mightn't have had time to go on with the letter just then, suggested the inspector." We know someone was with him a half-past nine. If that visitor turned up as soon as you left, and after he went, Miss Ackroyd came in to say good-night -- well, he wouldn't be able to go on with the letter until close upon ten o'clock."

"Ye -- es." I said rather doubtfully.

"Anyway, we can find out the truth about the telephone call from the exchange. If it was put through from here, I don't see how anyone else but Parker could have sent it. Depend upon it, he's our man. But keep it dark -- we don't want to alarm him just yet, till we've got all the evidence. I'll see to it he doesn't give us the slip. To all appearances we'll be concentrating on your mysterious stranger."

He rose from where he had been sitting astride the chair belonging to the desk, and crossed over to the still form in the arm-chair.

"Yes," he said, nodding at it. "Quite a work of art. There can't be many of them about."

"The weapon ought to give us clue," he remarked, looking up. "It's something quite unique -- a curio, I should think, by the look of it."

He bent down, surveying the handle attentively, and I heard him give a grunt of satisfaction. Then, very gingerly he pressed his hands down below the hilt and drew the blade out from the wound. Still carrying it so as not to touch the handle, he placed it a wide china mug which adomed the mantelpiece.

It was indeed a beautiful object. A narrow, tapering blade, and a hilt of elaborately intertwined metals of curious and careful workmanship. He touched the blade gingerly with his finger, testing its sharpness, and made an appreciative grimace.

"May I examine the body properly now?" I asked.

"Lord, what an edge," he exclaimed. A child could drive that into a man -- as easy as cutting butter. A dangerous sort of toy to have about."

He nodded. "Go ahead."

I made a thorough examination.

"Well?" said the inspector, when I had finished.

I took the look.

He stood off a few steps to judge of his effect.

I'll spare you the technical language," I said. "We'll keep that for the inquest. The blow was delivered by a right-handed man standing behind him, and death must have been instantaneous. By the expression on the dead man's face, I should say that the blow was quite unexpected. He may have died without knowing who his assailant was."

"I dare say they're not apparent to you, but can see them clearly enough." He lowered his voice. "Fingerprints!"

I do not see why I should be supposed to be totally devoid of intelligence. After all, I read detective stories, and the newspapers, and am a man of quite average ability. If there had been toe marks on the dagger handle, now, that would had been quite a different thing. I would then have registered any amount of surprise and awe.

"Butlers can creep about as soft-footed as cats," said Inspector Davis. "There's not going to be much mystery about this crime. Take a look at the hilt of that dagger."

"Yes." I said mildly. "I guessed that."

I think the inspector was annoyed with me for declining to get thrilled. picked up the china mug and invited to accompany him to the billiard room.

"Ever seen this before, Mr Raymond?"

Locking the outer door behind us again, we made our way to the billiard room, where we found Geoffrey Raymond. The inspector held up his exhibit.

"Nice young fellow that," said the inspector. "Something honest and ingenuous about him." I agreed. In the two years that Geoffrey Raymond has been secretary to Ackroyd, I have never seen him ruffled or out of temper. And he has been, I know, a most efficient secretary.

"Why -- I believe -- I'm almost sure that is a curio given to Mr Ackroyd by Major Blunt. It comes from Morocco -- no, Tunis. So the crime was committed with that? What an extraordinary thing. It seems almost impossible, and yet there could hardly be two daggers the same. May I fetch Major Blunt?" Without waiting for an answer, he hurried off.

"I want to see if Mr Raymond can tell us anything about this dagger," he explained.

"Absolutely. No doubt whatever."

"You recognized it, then?"

It was the secretary who answered.

"Yes, doctor?" said the inspector encouragingly.

"Major Blunt hasn't looked at it yet," objected the inspector.

"It's so trivial," I explained apologetically. "Only that when I arrived last night for dinner I heard the lid of the silver table being shut down in the drawing-room." I saw profound scepticism and a trace of suspicion on the inspector's countenance.

"Where was this -- er -- curio usually kept? Can you tell me that, sir?"

"I was right," said Raymond excitedly. "It is the Tunisian dagger."

In a minute or two Raymond returned, accompanied by Blunt.

"You said nothing about it," said the inspector suspiciously.

Blunt nodded.

The others looked at me.

"Wrong moment," said Blunt. "Lot of harm done by blurting out things at the wrong time." He returned the inspector's stare placidly enough.

The latter grunted at last and turned away. He brought the dagger over to Blunt.

"What?" I exclaimed.

"It's nothing," said the inspector again, still encouragingly.

"In the silver table in the drawing-room."

"Saw it the moment I came into the study," said the quiet man.

"You're quite sure about it, sir. You identify it positively?"

"I don't think I went near the silver table," she said, when the inspector had posed his question. "I was looking to see that all the flowers were fresh. Oh! yes, I remember now. The silver table was open -- which it had no business to be, and I shut the lid down as I passed."

A few minutes later Miss Russell, summoned by Parker, entered the room.

The inspector heard me to the end.

"We'd better get hold of the housekeeper," remarked the inspector, and pulled the bell.

"I can't say I'm sure," she replied. "I didn't stop to look. I knew the family would be down any minute, and I wanted to get away."

Miss Russell looked at the weapon composedly.

"Was the dagger in its place when you were looking over the contents?" he asked.

"I don't know," I said. "I can't say I remember noticing it -- but, of course, it may have been there all the time."

She looked at him aggressively.

"How did you know it was the silver table lid?" I was forced to explain in detail -- a long, tedious explanation which I would infinitely rather not have had to make.

"I see," said the inspector. "Can you tell me if this dagger was in its place then?"

Raymond answered for me. "Yes, the left-hand window."

"Thank you," said the inspector. There was just a trace of hesitation in his manner, as though he would have liked to question her further, but Miss Russell clearly accepted the words as a dismissal, and glided from the room.

"And the window was open?"

"They were both ajar."

"Rather a Tartar, I should fancy, eh?" said the inspector, looking after her. "Let me see. This silver table is in front of one of the windows, I think you said, doctor?"

"Well, I don't think we need go into the question much further. Somebody -- I'll just say somebody -- could get that dagger any time he liked, and exactly when he got it doesn't matter in the least. I'll be coming up in the morning with the chief constable, Mr Raymond. Until then, I'll keep the key of that door. I want Colonel Melrose to see everything exactly as it is. I happen to know that he's dining out the other side of the county, and, I believe, staying the night…"

We watched the inspector take up the jar.

"A little obvious," murmured my companion. "So Parker is the suspect, is he? Shall we oblige Inspector Davis with a set of our fingerprints also?" He took two cards from the card tray, wiped them with his silk handkerchief, then handed one to me and took the other himself. Then, with a grin, he handed them to the police inspector.

A few minutes later as I came out of the billiard room with Raymond, the latter gave a low chuckle of amusement.

"Souvenirs," he said. "No. 1. Dr Sheppard, No. 2, my humble self. One from Major Blunt will be forthcoming in the morning." Youth is very buoyant. Even the brutal murder of his friend and employer could not dim Geoffrey Raymond's spirits for long. Perhaps that is as it should be. I do not know. I have lost the quality of resilience long since myself.

I felt the pressure of his hand on my arm, and followed the direction of his eyes. Inspector Davis seemed to be inviting Parker's opinion of a small pocket diary.

"I shall have to pack this carefully," he observed. "It's going to be an important piece of evidence in more ways than one."

"Parker!" said my sister. "Fiddlesticks! That inspector must be a perfect fool. Parker indeed! Don't tell me." With which obscure pronouncement we went up to bed.

It was very late when I got back, and I hoped that Caroline would have gone to bed. I might have known better.

She had hot cocoa waiting for me, and whilst I drank it, she extracted the whole history of the evening from me. I said nothing of the blackmailing business, but contented myself with giving her the facts of the murder.

"The police suspect Parker," I said, as I rose to my feet and prepared to ascend to bed. "There seems a fairly clear case against him."