Having explained who I was, I followed the men in and assisted them in making a careful and minute examination of the place.

Search for the weapon with which the crime had been committed proved fruitless; hence it was plain that the murderer had carried it away. There were no signs whatever of a struggle, and nothing to indicate that the blow had been struck by any burglar with a motive of silencing the prostrate man.

The room was a large front one on the first floor, with two French windows opening upon a balcony formed by the big square portico. Both were found to be secured, not only by the latches, but also by long screws as an extra precaution against thieves, old Mr. Courtenay, like many other elderly people, being extremely nervous of midnight intruders. The bedroom itself was well furnished in genuine Sheraton, which he had brought up from his palatial home in Devonshire, for the old man denied himself no personal comfort. The easy chair in which he had sat when I had paid my visit was still in its place at the fireside, with the footstool just as he had left it; the drawers which we opened one after another showed no sign of having been rummaged, and the sum result of our investigations was absolutely nil.“It looks very much as though someone in the house had done it,” whispered the inspector seriously to me, having first glanced at the door to ascertain that it was closed.

“Yes,” I admitted, “appearances certainly do point to that.”

“Who was the young lady who met us downstairs?” inquired the detective sergeant, producing a small note-book and pencil.

“Miss Ethelwynn Mivart, sister to Mrs. Courtenay.”

“And is Mrs. Courtenay at home?” he inquired, making a note of the name.

“No. We have sent for her. She’s staying with friends in London.”

“Hulloa! There’s an iron safe here!” exclaimed one of the men rummaging at the opposite side of the room. He had pulled away a chest of drawers from the wall, revealing what I had never noticed before, the door of a small fireproof safe built into the wall.

“Is it locked?” inquired the inspector.

The man, after trying the knob and examining the keyhole, replied in the affirmative.

“Keeps his deeds and jewellery there, I suppose,” remarked one of the other detectives. “He seems to have been very much afraid of burglars. I wonder whether he had any reason for that?”

“Like many old men he was a trifle eccentric,” I replied. “Thieves once broke into his country house years ago, I believe, and he therefore entertained a horror of them.”We all examined the keyhole of the safe, but there was certainly no evidence to show that it had been tampered with. On the contrary, the little oval brass plate which closed the hole was rusty, and had not apparently been touched for weeks.

While they were searching in other parts of the room I directed my attention to the position and appearance of my late patient. He was lying on his right side with one arm slightly raised in quite a natural attitude for one sleeping. His features, although the pallor of death was upon them and they were relaxed, showed no sign of suffering. The blow had been unerring, and had no doubt penetrated to the heart. The crime had been committed swiftly, and the murderer had escaped unseen and unheard.

The eider-down quilt, a rich one of Gobelin blue satin, had scarcely been disturbed, and save for the small spot of blood upon the sheet, traces of a terrible crime were in no way apparent.

While, however, I stood at the bedside, at the same spot most probably where the murderer had stood, I suddenly felt something uneven between the sole of my boot and the carpet. So intent was I upon the examination I was making that at first my attention was not attracted by it, but on stepping on it a second time I looked down and saw something white, which I quickly picked up.

The instant I saw it I closed my hand and hid it from view.

Then I glanced furtively around, and seeing that my action had been unobserved I quickly transferred it to my vest pocket, covering the movement by taking out my watch to glance at it.

I confess that my heart beat quickly, and in all probability the colour at that moment had left my face, for I had, by sheer accident, discovered a clue.

To examine it there was impossible, for of such a character was it that I had no intention, as yet, to arouse the suspicions of the police. I intended at the earliest moment to apprise my friend, Ambler Jevons, of the facts and with him pursue an entirely independent inquiry.

Scarcely had I safely pocketed the little object I had picked up from where the murderer must have stood when the inspector went out upon the landing and called to the constable in the hall:

“Four-sixty-two, lock that door and come up here a moment.”

“Yes, sir,” answered a gruff voice from below, and in a few moments the constable entered, closing the door after him.

“How many times have you passed this house on your beat to-night, four-sixty-two?” inquired the inspector.

“About eight, sir. My beat’s along the Richmond Road, from the Lion Gate down to the museum, and then around the back streets.”

“Saw nothing?”

“I saw a man come out of this house hurriedly, soon after I came on duty. I was standing on the opposite side, under the wall of the Gardens. The lady what’s downstairs let him out and told him to fetch the doctor quickly.”

“Ah! Short, the servant,” I observed.

“Where is he?” asked the inspector, while the detective with the ready note-book scribbled down the name.

“He came to fetch me, and Miss Mivart has now sent him to fetch her sister. He was the first to make the discovery.”

“Oh, was he?” exclaimed the detective-sergeant, with some suspicion. “It’s rather a pity that he’s been sent out again. He might be able to tell us something.”

“He’ll be back in an hour, I should think.”

“Yes, but every hour is of consequence in a matter of this sort,” remarked the sergeant. “Look here, Davidson,” he added, turning to one of the plain-clothes men, “just go round to the station and send a wire to the Yard, asking for extra assistance. Give them a brief outline of the case. They’ll probably send down Franks or Moreland. If I’m not mistaken, there’s a good deal more in this mystery than meets the eye.”

The man addressed obeyed promptly, and left.

“What do you know of the servants here?” asked the inspector of the constable.

“Not much, sir. Six-forty-eight walks out with the cook, I’ve heard. She’s a respectable woman. Her father’s a lighterman at Kew Bridge. I know ’em all here by sight, of course. But there’s nothing against them, to my knowledge, and I’ve been a constable in this sub-division for eighteen years.”“The man—what’s his name?—Short. Do you know him?”

“Yes, sir. I’ve often seen him in the ‘Star and Garter’ at Kew Bridge.”

“Drinks?”

“Not much, sir. He was fined over at Brentford six months ago for letting a dog go unmuzzled. His greatest friend is one of the gardeners at the Palace—a man named Burford, a most respectable fellow.”

“Then there’s no suspicion of anyone as yet?” remarked the inspector, with an air of dissatisfaction. In criminal mysteries the police often bungle from the outset, and to me it appeared as though, having no clue, they were bent on manufacturing one.

I felt in my vest pocket and touched the little object with a feeling of secret satisfaction. How I longed to be alone for five minutes in order to investigate it!

The inspector, having dismissed the constable and sent him back to his post to unlock the door for the detective to pass out, next turned his attention to the servants and the remainder of the house. With that object we all descended to the dining-room.

Ethelwynn met us at the foot of the stairs, still wearing the shawl about her head and shoulders. She placed a trembling hand upon my arm as I passed, asking in a low anxious voice:

“Have you found anything, Ralph? Tell me.”

“No, nothing,” I replied, and then passed into the dining-room, where the nurse and domestics had been assembled.The nurse, a plain matter-of-fact woman, was the first person to be questioned. She explained to us how she had given her patient his last dose of medicine at half-past eleven, just after Miss Mivart had wished her good-night and retired to her room. Previously she had been down in the drawing-room chatting with the young lady. The man Short was then upstairs with his master.

“Was the deceased gentleman aware of his wife’s absence?” the inspector asked presently.

“Yes. He remarked to me that it was time she returned. I presume that Short had told him.”

“What time was this?”

“Oh! about half-past ten, I should think,” replied Nurse Kate. “He said something about it being a bad night to go out to a theatre, and hoped she would not take cold.”

“He was not angry?”

“Not in the least. He was never angry when she went to town. He used to say to me, ‘My wife’s a young woman, nurse. She wants a little amusement sometimes, and I’m sure I don’t begrudge it to her.’”

This puzzled me quite as much as it puzzled the detective. I had certainly been under the impression that husband and wife had quarrelled over the latter’s frequent absences from home. Indeed, in a household where the wife is young and the husband elderly, quarrels of that character are almost sure to occur sooner or later. As a doctor I knew the causes of domestic infelicity in a good many homes. Men in my profession see a good deal, and hear more. Every doctor could unfold strange tales of queer households if he were not debarred by the bond of professional secrecy.

“You heard no noise during the night?” inquired the inspector.

“None. I’m a light sleeper as a rule, and wake at the slightest sound,” the woman replied. “But I heard absolutely nothing.”

“Anyone, in order to enter the dead man’s room, must have passed your door, I think?”

“Yes, and what’s more, the light was burning and my door was ajar. I always kept it so in order to hear if my patient wanted anything.”

“Then the murderer could see you as he stood on the landing?”

“No. There’s a screen at the end of my bed. He could not see far into the room. But I shudder to think that to-night I’ve had an assassin a dozen feet from me while I slept,” she added.

Finding that she could throw no light upon the mysterious affair, the officer turned his attention to the four frightened domestics, each in turn.

All, save one, declared that they heard not a single sound. The one exception was Alice, the under housemaid, a young fair-haired girl, who stated that during the night she had distinctly heard a sound like the low creaking of light shoes on the landing below where they slept.

This first aroused our interest, but on full reflection it seemed so utterly improbable that an assassin would wear a pair of creaky boots when on such an errand that we were inclined to disregard the girl’s statement as a piece of imagination. The feminine mind is much given to fiction on occasions of tragic events.

But the girl over and over again asserted that she had heard it. She slept alone in a small room at the top of the second flight of stairs and had heard the sound quite distinctly.

“When you heard it what did you do?”

“I lay and listened.”

“For how long?”

“Oh, quite a quarter of an hour, I should think. It was just before half-past one when I heard the noise, for the church clock struck almost immediately afterwards. The sound of the movement was such as I had never before heard at night, and at first I felt frightened. But I always lock my door, therefore I felt secure. The noise was just like someone creeping along very slowly, with one boot creaking.”

“But if it was so loud that you could hear it with your door closed, it is strange that no one else heard it,” the detective-sergeant remarked dubiously.

“I don’t care what anybody else heard, I heard it quite plainly,” the girl asserted.

“How long did it continue?” asked the detective.

“Oh, only just as though someone was stealing along the corridor. We often hear movements at nights, because Short is always astir at two o’clock, giving the master his medicine. If it hadn’t ha’ been for the creaking I should not have taken notice of it. But I lay quite wide awake for over half an hour—until Short came banging at our doors, telling us to get up at once, as we were wanted downstairs.”

“Well,” exclaimed the inspector, “now, I want to ask all of you a very simple question, and wish to obtain an honest and truthful reply. Was any door or window left unfastened when you went to bed?”

“No, sir,” the cook replied promptly. “I always go round myself, and see that everything is fastened.”

“The front door, for example?”

“I bolted it at Miss Ethelwynn’s orders.”

“At what time?”

“One o’clock. She told me to wait up till then, and if mistress did not return I was to lock up and go to bed.”

“Then the tragedy must have been enacted about half an hour later?”

“I think so, sir.”

“You haven’t examined the doors and windows to see if any have been forced?”

“As far as I can see, they are just as I left them when I went to bed, sir.”

“That’s strange—very strange,” remarked the inspector, turning to us. “We must make an examination and satisfy ourselves.”

The point was one that was most important in the conduct of the inquiry. If all doors and windows were still locked, then the assassin was one of that strange household.

Led by the cook, the officers began a round of the lower premises. One of the detectives borrowed the constable’s bull’s-eye and, accompanied by a second officer, went outside to make an examination of the window sashes, while we remained inside assisting them in their search for any marks.

Ethelwynn had been called aside by one of the detectives, and was answering some questions addressed to her, therefore for an instant I found myself alone. It was the moment I had been waiting for, to secretly examine the clue I had obtained.

I was near the door of the morning room, and for a second slipped inside and switched on the electric light.

Then I took from my vest pocket the tiny little object I had found and carefully examined it.

My heart stood still. My eyes riveted themselves upon it. The mystery was solved.

I alone knew the truth!