Colwyn compared the caps which had dropped on the table with the one he had found upstairs. They were the same size. He tried the solitary cap on the nipple, and found that it fitted perfectly. As he did so, he saw something resembling a thread of yellow wool caught in the twisted steel of the hammer. It was a minute fragment, so small as to be hardly noticeable. Colwyn was quite unable to determine what it was, but its presence there puzzled him considerably, and he was at a loss to understand how it had got caught in the hammer of the pistol. It struck him that the thread might be khaki, and his mind reverted to his earlier discovery of the patch of khaki in the wood outside the moat-house.

It was with the hope of finding out whether this pistol had been lately used that Colwyn turned his attention to the velvet-lined interior of the case. The inside was divided into a large compartment for the pistols and several small lidded s.p.a.ces. In one of these he found some shot, a box of percussion caps, and a powder-flask half-full of common gunpowder. Another s.p.a.ce contained implements for cleaning the pistols. The contents of the next compartment puzzled him. There were some odd lengths of knotted string, and a coil of yellow tubular fabric, about the thickness of his little finger, some inches in length. Colwyn recognized it at once. It was the wick of a tinder-lighter, then being sold by thousands by English tobacconists to replace a war-time scarcity of matches, and greatly used by cigarette smokers.

The mystery of the presence of the wick in the pistol-case was not lessened because it enabled Colwyn to identify the tiny yellow fragment adhering to the c.o.c.k of the pistol. He picked up the wick and observed that one end was cut clean, but the other end was blackened and burnt. At that discovery there entered his mind the first prescient warning of the possibility of some deep plan in which the pistol and the wick played important parts. With his brain seeking for a solution of that possibility, he proceeded to examine the pieces of string.

They were odd lengths of ordinary thick twine, but they all seemed to consist of loose ends which had been knotted together. It was not until Colwyn took them out of the compartment that he noticed an amazing peculiarity about them. Each piece of knotted string was burnt at both ends.

There are some discoveries which spring into the mind with shattering swiftness. This was one of them. A revelation seemed to come to Colwyn as light from the sky at midnight, which, lays everything bare in one frightful flash.

"Is it possible?"

He felt as though these words rushed from him like a thunder-roll reverberating through the empty s.p.a.ce around him. But his set lips had not uttered a single sound. With tingling nerves he proceeded to carry out an experiment. He first laid the wick of the tinder-lighter along the stock of the pistol, just behind the hammer. He next took up one of the lengths of string, and pulling back the hammer and the trigger of the pistol, proceeded to bind them both firmly back with the string, which he pa.s.sed twice round the wick. When he had tied the string tight he lit a match and applied it to the end of the wick which was farthest from the string. His idea was to see whether this extemporized fuse would creep along the stock of the pistol, burn the string, and release the bound c.o.c.k and trigger.

The wick smouldered and glowed, and began to creep towards the string, which crossed the stock of the pistol about three inches from the burning end. Colwyn took out his watch and timed its progress. In four minutes the first inch of the wick was consumed, and the spark at the end continued to creep sullenly forward in a dull red glow. In another eight minutes it reached the string, and Colwyn eagerly watched the process of the burning of the binding. The string singed, smouldered, and when nearly severed, sprang apart under the pressure of the hammer and trigger it had been holding back. The released hammer fell with full force on the cap on the nipple, and exploded it.

There, then, seemed the explanation. Mrs. Heredith had been shot with Nepcote's revolver, but it was not the deliberately deadened sound of that slight weapon which had startled the guests in the dining-room on the night of the murder. The report they had heard was made by the heavier pistol in front of him. It was a ruse of terrifying simplicity but diabolical ingenuity. The wick of the tinder-lighter was an admirable slow match, obtainable in any tobacconist's shop for a few pence, which, by means of this trick, had established a false alibi for the actual murderer by causing the report which had reached the dining-room, and sent the inmates hastening upstairs to ascertain the cause. The shot which had mortally wounded Mrs. Heredith must have been fired before.

How long before? Obviously not very long. That would have been dangerous to the murderer's plans. He had to consider two things. There was the chance of somebody entering the room before the false charge exploded, and the possibility that the coldness of the body of his victim might arouse medical suspicions. Colwyn did not think that the criminal had avoided killing Mrs. Heredith so as to ensure against that risk of discovery. The infliction of a mortal wound which failed to cause immediate death not only required a high degree of anatomical knowledge, but left the door open to a dying confession which might have upset the whole plan. Fate had helped the murderer to that extent.

But the murderer owed more than that to Fate. It was to that grim G.o.ddess he was indebted for the last wonderful touch of actuality which lifted the whole contrivance so superbly above the realm of artifice. Suspicion was in the last degree unlikely in any case, but Hazel Rath's entry and loud scream, just before the moment fixed for the explosion, ensured complete success by adding a natural verisimilitude which might have deceived the very Spirit of Truth. Colwyn esteemed himself fortunate indeed in lighting on what he believed to be the facts. Who could have imagined a situation in which whimsical Destiny had ironically stooped down from her high place to dabble ign.o.bly in a murderer's ghastly plot?

The one point which perplexed Colwyn was the successful concealment of the pistol on the night of the murder. That part of the plan was as essential to the murderer as the false report, but it seemed strange that the pistol had not been discovered when the room was searched. An examination of the grate upstairs might reveal the reason.

Before leaving the gun-room Colwyn replaced one of the pistols and restored the case as he had found it to its original position. He carried away with him the pistol which had been used.

When he reached the upstairs bedroom he locked the door before proceeding to examine the fireplace. It was immediately apparent to him that the pistol had not been placed in the grate or beneath it. Either place would have meant discovery when the room was searched. It was a careful examination of the upper portion of the grate which suggested the hiding-place. The weapon could have been safely hidden within the broad iron f.l.a.n.g.e running round the open damper of the grate.

The complete revelation of this portion of the murderer's design came to Colwyn as he was pa.s.sing his hand over the inner surface of this ledge. It was a register grate, and the s.p.a.ce at the back had not been filled in. The murderer, when concealing the pistol at the top of the grate, had only to balance it carefully on the f.l.a.n.g.e, with the muzzle pointing into the room, to ensure that the recoil from the report would cause the weapon to fall into the deep hole between the back of the grate and the chimney.

This additional proof of the murderer's perverted intelligence impressed Colwyn as much as the mechanism for the false report. The pistol, blindly recoiling and jumping behind the grate after the explosion of the blank charge, was almost as effectually concealed as at the bottom of the sea, and might have remained there for years without discovery. Colwyn plunged his arm into the hole, but could not reach the bottom.

But the murderer had more in his mind than the effectual concealment of the pistol, important though that was to him. The grate was an excellent choice for two other reasons. It carried the slight vapour from the tinder wick up the chimney, and the convex iron interior formed an excellent sounding board which would enhance the sound of the report. Truly the dark being who had planned it all had left nothing to chance. He had foreseen everything. His handiwork bore the stamp of unholy genius.

Who had done this thing? Who had sought, with such patient cunning, to upset those evidential principles by which blind Justice gropes her hesitating way to Truth? In concocting his masterpiece of malignant ingenuity the murderer had worked alone. His only accomplice-apart from the after-hand of Fate-was a piece of automatic mechanism which had done his bidding secretly, and would never have betrayed him. It was this ability to work alone, scheming and brooding in solitary concentration until the whole of the horrible conception had been perfected in every degree, which stamped the designer as a ferocious criminal of unusual mould, remorseless as a tiger, with a neurasthenic mind swayed by the unbridled savagery of natural impulse.

As Colwyn meditated over the murder, his original impression of the guests a.s.sembled in the dining-room downstairs in a premeditated scene set for its production came back to him with renewed force. The murderer had taken his part in that scene as one of the unconscious audience, dining and taking his share in the conversation, while his secret consciousness was strained to an intense antic.i.p.ation of the false signal from his mechanical accomplice upstairs. Colwyn could picture him joining in the mockery of meaningless phrases with dry lips, his ears listening for every sound, his eyes covertly watching the crawling hands of the clock. Then, when the crack had pealed forth, he had been able to exchange suspense for action, and rush upstairs with the others, confident in the feeling that, let suspicion point where it would, it could not fall on him.

But the murderer had not foreseen the scream which preceded the shot. How had he comported himself under the shock of that cry, which was outside the region of his calculations? He had not time to reflect upon its origin, to investigate its source. He had to steel his nerves to face it because he dared not do otherwise. But its sudden effect on the nerve centres of his brain, previously strained almost to the breaking point, must have brought him to the verge of a subsequent collapse.

Colwyn believed he saw the end in sight. The presumptions, the facts, and the motive all pointed to one figure as the murderer of Violet Heredith. She had been killed from the dual motive of punishment in her own case and vengeance on a greater offender than herself. The alibi had been devised to ensure a tremendous revenge on the man by bringing him to the gallows as her supposed murderer. That part of the plan had gone astray, so the murderer, in the fanatical resolve of his latent fixed idea, had recourse to a further expedient as daring and original as the scheme which failed. The second instrument had been the means of his own undoing.

But as he reached this final stage of his reasoning, Colwyn stopped short in something like dismay. He had left a point of vital importance out of his calculations. If the murderer was the man he thought, he was downstairs in the dining-room at the time the false shot was fired. Then whose hand had clutched Hazel Rath's throat in the murdered woman's bedroom upstairs, just before the shot was fired?

Colwyn slowly paced up and down the room in the midnight silence, conning all the facts over again in the light of this overlooked incident.

CHAPTER XXVIII

The three dined together in the big dining-room almost in silence. Musard and Philip Heredith had not returned until after six, and their first knowledge of Colwyn's presence was by some oversight deferred until they met at the dinner table. In the awkwardness of that surprise they sat down to dine, and Musard's half-hearted efforts to start a conversation met with little response from his companions. Colwyn was preoccupied with his own thoughts, which apparently affected his appet.i.te, for he sent away dish after dish untouched. Phil hastened the service of the meal considerably, as though he were anxious to get it over as speedily as possible in order to hear what the detective had to say. As soon as the dessert was on the table he turned to Colwyn eagerly and asked him if he had any news.

"I have many things to say," was the response.

"In that case, shall we take our coffee into the smoking-room?" suggested Musard with a slight glance at the hovering figure of the butler.

"I prefer to remain here, if you do not mind," said Colwyn.

Musard shot a puzzled look at him, which the detective met with a clear cold gaze which revealed nothing. There was another silent pause while they waited for the butler to leave the room. But Tufnell was pouring out coffee and handing cigars with the slow deliberation of a man sufficiently old to have outlived any illusions about the value of time. Philip Heredith lit a cigarette. Musard waved away the cigar-box and produced a strong black cheroot from the crocodile-skin case. Colwyn declined a cigar, and his coffee remained untasted in front of him.

"You can leave the room now, Tufnell," said Phil impatiently. "Do not return until I ring. We do not wish to be disturbed."

Tufnell bowed and left the room. As he did so Colwyn pushed back his chair and walked across to the window, where he stood for a few moments looking out. A wan young moon gleamed through the black tapestry of the avenue of trees, pointing white fingers at the house and plunging the old garden into deep pools of shadow. The trees huddled in their rows, whispering menacingly, and stretching half-stripped branches to the silent sky.

Colwyn returned to the table and confronted the two men who were awaiting him. He glanced from one to the other of their attentive faces, and said abruptly:

"Hazel Rath is innocent."

"I was certain of it." Philip Heredith's hand came down emphatically on the table in front of him as he made this declaration. "I knew it all along," he added in additional emphasis.

"This is an amazing piece of news, Mr. Colwyn," said Musard, turning earnestly to the detective. "Who, then-"

Colwyn made a detaining gesture.

"Wait," he said. "I cannot tell you that just yet." He turned to Phil, whose dark eyes were fixed on his face. "It was you who asked me to try and solve the mystery of your wife's death. It is to you that my explanation is due. Shall I speak freely in Mr. Musard's presence, or would you rather hear me alone?"

"I can go to the smoking-room," said Musard, rising as he spoke.

But Phil waved him to his seat again.

"No, no, Musard, stay where you are. There is no reason why you should not hear what Mr. Colwyn has to say. Your advice may be needed," he added as an afterthought.

"So be it," said Colwyn. "Then I had better commence by informing you that Hazel Rath has broken her silence. She has made a statement to the police, which, whilst affirming her innocence, does very little to clear up the murder. Her story, briefly, is that she went up to the left wing about half-past seven, noticed that Mrs. Heredith's room was in darkness, and went in under the impression that she might be ill and in need of a.s.sistance. She groped her way across the room to turn on the light, and she had reached the head of the bed and was feeling for the switch when a hand clutched her throat. She screamed wildly, and the hand fell away. A moment afterwards the report of a shot filled the room. She found the electric switch, and turned on the light. The first thing she saw was a revolver-Nepcote's revolver-lying at her feet near the head of the bed. Then her eyes turned to the bed, and she saw Mrs. Heredith, bleeding from the mouth and nose. While she was attempting to render her some a.s.sistance she heard footsteps on the stairs, and thought of her own safety. She switched off the light and ran out, carrying the revolver and the handkerchief with which she had been wiping the blood from the dying woman's lips. She was just in time to conceal herself behind the curtains in the corridor and escape the observation of those who were rushing upstairs. There she stayed while the rooms were searched, and was afterwards able to steal downstairs un.o.bserved and gain the safety of her mother's apartments, where the revolver and the handkerchief were subsequently found."

"This is a remarkable story," said Musard slowly. "Do the police believe it?"

"They do not, but I have my reasons for thinking it true," responded Colwyn. "The next step in the story of how this unhappy girl became the victim of an apparently irreb.u.t.table set of circ.u.mstances through her own silence, has to do with another person's secret visit to the moat-house on the night of the murder. That person was a man, who came to return to Mrs. Heredith the necklace which we subsequently discovered to be missing from her locked jewel-case. It is not necessary to relate how the necklace came to be in his hands. He had undertaken to return the necklace from London to enable Mrs. Heredith to produce it on the following day, and it was arranged between them that when he reached the moat-house that night he was to enter the unused door in the left wing, which was to be previously unlocked for him, and was to wait on the staircase until Mrs. Heredith was able to steal down to him and obtain the jewels. That plan was upset by Tufnell finding the door unlocked, and locking it again before his arrival. When he did arrive he found himself unable to get in."

"Stop a moment," exclaimed Musard hoa.r.s.ely. "This story goes too deep for me. Who is this man? Do you know him? Has he anything to do with the murder?"

"Yes, I know him, and he has much to do with the murder," said the detective. "Shall I mention his name, Mr. Heredith?"

Phil nodded, as though he were unable to speak.

"The man is Captain Nepcote."

"Nepcote!" A swift flash of wrath came into Musard's heavy dark eyes as he uttered the name. Then, in a wider understanding of the sordid interpretation of Colwyn's story, he hesitatingly added: "I think I see. It was Nepcote's revolver. Was it he who shot Violet?"

"Before answering that question it is necessary to give Nepcote's explanation of his actions on that night. His own story is that he did not enter the house. He says that while he was waiting outside he heard a scream followed by a shot, and he then hid in the woods in front of the house until he thought it safe to return to London. He declares he is innocent of the murder."

"That is a lie!" Phil burst forth. "Who will believe him?" He stopped abruptly, and turned fiercely to Colwyn. "How do you know Nepcote said this?" he demanded.