The gun-room was dark and silent as a vault. In the deep recesses the armoured phantoms of dead and gone Herediths seemed to be watching the intruder with hidden eyes behind the bars of their tilting helmets and visored salades. The light of Colwyn's electric torch fell on the shell of a mighty warrior who stood with one steel gauntlet raised as though in readiness to defend the honour of his house. His initials, "P.H.," were engraved on his giant steel breast, and his steel heels flourished a pair of fearful spurs, with rowels like daggers. Standing by this giant was a tiny suit of armour, not more than three feet in height, which might have been worn by a child.

"A strange pair," murmured Colwyn, pausing a moment to glance at them. As he turned his light in their direction his eye was caught by an inscription cut in the stone above their heads, and he drew nearer and read that the large suit had been worn by the former Philip Heredith, "A True Knight of God." The smaller suit had been made for a dwarf attached to his house, who had followed his master through the Crusades, and fought gallantly by his side.

Colwyn turned away and flashed his light along the walls in search of the case of pistols. His torch glanced over the numerous trophies adorning the walls, lances, swords, daggers, steel head-pieces, bascinets, peaked morions—relics of a departed age of chivalry, when knights quarrelled prettily for ladies, and fighting was fair and open, before civilization had enriched warfare with the Christian attributes of gas-shells, liquid fire, and high explosives. Then the light fell on that which he was seeking—a dark oblong box, with brass corners, and a brass handle closing into the lid.

Colwyn lifted the case down from the embrasure in which it was placed, and carried it to the bagatelle table. A brief examination of the lock satisfied him that it was too complicated and strong to be picked or broken. It was curiously wrought in brass, of an intricate antique pattern which would have puzzled a modern locksmith. He turned the case over, and saw that the bottom had been mortised and screwed. The screws had been deeply countersunk, and were embedded in rust, but a few were loose with age. Colwyn unscrewed these loose ones with his pocket-knife, and then set about unloosening the others.

It was a tedious task, but Colwyn lightened it with the aid of a bottle of gun oil which he found in one of the presses. Some of the screws yielded immediately to that bland influence, and came out easily. Others remained fast in the intractable way of rusty screws, but Colwyn persevered, and by dint of oiling, coaxing, and unscrewing, finally had the satisfaction of seeing all the screws lying in a little greasy brown heap on the faded green cloth of the bagatelle table. The next thing was to lever off the bottom of the lid. That was not difficult, because the glue in the mortises had long since perished. Soon the bottom was lying on the table beside the screws, and the interior of the case revealed.

The pair of weapons which Colwyn lifted from the case were horse pistols of a period when countryfolk feared to ride abroad without some such protection against highwaymen. They were superior specimens of their type. They were beautifully made, rich in design and solid in form, with ebony stocks and chased silver mountings. The long barrels were damascened, and the carved handles terminated in flat steel butts which would have cracked the pate of any highwayman if the shot missed fire. As Colwyn anticipated, the pistols were muzzle-loaders. The cock, which laid over considerably, was in the curious form of a twisted snake. When the trigger was pulled the head of the snake fell on the nipple.

Colwyn examined them carefully. He first ascertained that they were unloaded by probing them with the ramrod which was attached to each by a steel hinge. Then he ran his finger round the inside of the muzzles to ascertain whether either pistol had been recently fired. One was clean, but from the muzzle of the other he withdrew a finger grimed with gunpowder. While he was doing this his other hand came in contact with something slightly uneven in the smooth metal surface of the butt. He turned the pistol over, and noticed a small inner circle in the flat steel. It was a small hinged lid, which hid a pocket in the handle. He raised the little lid with his finger-nail, and a shower of percussion caps fell on the bagatelle table. This contrivance for holding caps was not new to Colwyn. He had seen it in other old-fashioned muzzle-loaders.

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 spaces. In one of these he found some shot, a box of percussion caps, and a powder-flask half-full of common gunpowder. Another space 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 cock 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 space 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 passed 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 cock 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 goddess 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 ignobly 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 flange 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 passing his hand over the inner surface of this ledge. It was a register grate, and the space 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 flange, 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 assembled 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 anticipation 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.