I stood looking down at Michael Feddon's body. I was stunned. For the man I had just killed I cared nothing, felt no emotion. I had saved him from the drop; that was all. But, though I had been convinced that Danjuro's and my own suspicions were absolute fact, the full realization had come so suddenly that it clouded the mind.

Constance was here, and she was unharmed!

I had, indeed, penetrated into the very centre of this lair of the air-wolves, and already had enough evidence to hang the lot. For a minute the mingled joy and relief was so great that I could not grasp them.

The brandy bottle of Mr. Vargus was still on the side table. I stepped over the body—the leather belt which he had proposed as an instrument of correction for Constance was in full view—and helped myself sparingly. Almost immediately my brain cleared.

I listened intently. The two shots from my automatic had alarmed no one. The sinister house was as silent as before. It seemed quite certain that Feddon and Vargus alone remained to guard it. Even the two Tibetan mastiffs of which I had heard so much had disappeared.

To my right, the tall mirror swung on its hinges, and the lift beyond was lit by a globe in the roof. To what it led I did not know, probably some cellar where poor Constance and her maid were imprisoned, though a lift seemed superfluous. At any rate, Vargus—the next person to tackle—was down there, and it was long odds that I could not get the better of him. Moreover, and this was in my favour, he was expecting Feddon, and the arrival of the lift would not startle him at first, if he were close by.

I examined the lift. It was electrically operated, and of a type perfectly familiar to me, fitted with an automatic magnetic brake. I saw that it travelled from its secret recess behind the mirror to one other spot only, stopping nowhere on the way. A touch of the rope started it, and it would stop itself when its journey was done.

Well, there was no use waiting. Again I must plunge into the unknown. Connie was waiting! I wondered how honourable Danjuro was getting on, and laid myself long odds that he wasn't having such an exciting time as I was! How he would stare if he came back to "The Miners' Arms" in a few hours and found me there with Connie, and the artistic Mr. Vargus cooling down in the patent papier mÂchÉ handcuffs from Japan! Mr. Trewhella of the inn had shown me a large pig, which he called "Gladys," and of which he was fond. There was a vacant and stoutly-built sty next door, which would be an excellent place of confinement for the interpreter of Chopin!

... Yes, I thought these thoughts, even at that moment. I was madly exhilarated. Everything had gone so easily and well. I stepped into the lift humming a song. It was the old chanty that the pirates had roared in the inn two short hours ago:

"Fifteen men on the dead man's chest."

There was a looking-glass on one side of the lift—probably the thing had been bought entire at some sale—and I saw myself in it. The song died away. Whose was this grim and terrible face, gashed with deep lines, with eyes that smouldered with a red light? Mine? I have told you how Danjuro looked when the bloodhound that he was emerged for an instant from behind the bland Oriental mask. There was not a pin to choose between us.

The lift sank slowly. Every second I expected the soft jerk of its stopping. But the seconds went on. Down and down, what cellar was it that lay so low? Were we dropping to the centre of the earth? It seemed an age before the motion slowed, and I had already obtained an inkling of the truth when a dim archway rose up before me, and the machine came to rest.

This was no cellar. I was deep down in Tregeraint Mine, which must run under the house itself! In the necessity for fox-like caution, I did not follow out the thought—not yet. But I believe that the subconscious brain had already seen far into the mystery....

I stepped out into a mine cutting. The walls were cut in the rock, and the roof here and there shored up with heavy timber props. It was wide enough for two men to walk abreast, and quite eight feet high. Every fifteen yards or so hung a roughly-wired electric lamp, and the floor was beaten hard by the passage of many feet. The air was hot and stagnant.

I prowled down this passage without a sound, my pistol in my hand, ready to shoot at sight, but for what seemed an interminable time I met no one, and saw nothing but the damp walls, here and there sparkling with yellow pyrites and the green of copper.

There came at length a rough wooden door, which swung easily open, and beyond a much narrower and higher passage than before, a more natural cleft in the immemorial rock, it seemed, owing nothing to the agency of human hands. It dripped with water. Hitherto I had been walking on a level, now I trod a fairly steep descent, while the path was no longer straight, but full of fantastic twistings. Each moment the air grew cooler, and each moment a deep, murmurous noise, like very faint and muffled drums, grew louder.

The lights, now suspended from a thick and tarry cable, were less frequent than at first, and the place was full of shadows. But as for the noise, that could only be one thing, the Atlantic ground-swell. I was approaching the sea, doubtless by one of the old mine "adits," made for ventilation many years ago and long before the invention of the electric fan.

The narrow way ended in a door. It was latched but not locked, and I pushed it slowly open. Immediately there was a sense of vast and gloomy space. I say "gloomy," for it was not absolutely dark. Here and there hung dim, yellow lights....

Advancing a step or two upon a floor of hard earth on sand, I found myself in a vast cavern. It seemed as large as the shell of a cathedral, and for organ there was the plangent, echoing sound of sea waves. The sound came from my right, and was carried on a current of sweet, brine-laden air. Peering through the darkness, I seemed to be aware of a faint, ghostly radiance, a considerable distance away.

I had lost the capacity for amazement, but not of quick thinking. In a lightning flash of realization I knew that I had penetrated to the heart of Helzephron's secret, even before my thoughts arranged themselves in sequence. And then, as near as possible coincident with my stepping through the door, I heard a shout.

Someone had seen me....

The shout came from the other side of the long, aisle-shaped cave. Simultaneously, half-way up the side, at a height of thirty feet from the floor, there was a sudden illumination. I saw a broad ledge in the wall, railed round, with a ladder staircase descending from it. A little black figure was leaning over the rail, and it was from this that the shouting came. It did not need his words to tell me that here was a wireless station. I could see the drum and the battery shelf quite distinctly.

"A signal!" he shouted, and I knew that he took me for the dead man above. "They're coming back! The sky swarms with armed patrols and warships. They've had to run for it, but the Chief thinks he's shaken them off. I must switch on the guides!"

I gave an answering shout, keying my voice down to something like Feddon's bass growl.

"It's C.Q.D.!—C.Q.D.!" came in a shrill voice of alarm, and Mr. Vargus ran down the ladder like an ape.

C.Q.D.! The signal of "extreme danger." Well, I rather thought it was!

Where I stood I was in deep shadow, and my face could not possibly be seen. I was much the same height and build as the dead man, and Vargus ran down the cave without the least suspicion. He had gone to his left, my right, to where I had already seen a pale light, and I followed him, more slowly, at a distance of some ten yards. It was a natural instinct enough. My only idea was to silence him, find Constance, and fly from the horrible place. I could not know that I was making a fatal mistake.

I was running forward into complete understanding. The great cave turned a little to the right. It opened out every second until at length I saw the mouth, wide as that of the largest-sized hangar on an aerodrome, flooded with moonlight!

Opposite, sixty yards away, was a precipitous wall of black rock; between it and the mouth of the cave a terrible chasm, which fell sheer to the water. It was all clear now. Far above, on the top of the cliffs, was that fenced-in part with the "dangerous" notice boards. You will remember that I had lain down by the side of this fence and peered downwards. I had looked into the same gulf that I was now looking into from a much lower altitude. And the rock there overhung so greatly that there was no possible indication of the cave mouth where I now stood.

Moreover, the cave itself turned inward from the sea, running parallel to the cliff. From the sea, as from the land, the opening of the cave was entirely hidden.

Vargus was fumbling at a switch-board. He pulled down a vulcanite handle; there was a green spark, and lights at the top, bottom and sides of the entrance glowed out brightly.

Imagine an illuminated rabbit-hole in the side of a railway embankment, and you have an exact miniature of what this vast secret cave had now become. Go a little further and think of a bat whose lair was in this hole, and was guided to it by the lights....

Vargus snapped another and smaller switch. I watched him with a sense of complete detachment. I knew, as well as if I had been told, that he was lighting guiding lamps somewhere on the two headlands that guarded the entrance to the cave outside. No thought of danger came to me; I think joy at this complete discovery, and wonder at the stupendous cunning and achievement of it all were my only emotions.

"They may be here at any moment, Feddon. I tell you I don't like it at all. I told the Chief that it was madness not to lie low for a bit. But you know what he is. The Government has got the tip somehow, the Cornish seas are humming with enemies. That fellow, Custance, is smart as they make them...."

He was moving towards me as these words came from him in a nervous, disjointed stream of words. Then he saw me, and stopped bang in the middle of a sentence.

It was my moment.

"How do you do, Mr. Vargus," I said. "You mentioned my name. Indeed, you paid me a compliment for which I thank you. I thought I'd drop in for a chat. Sorry to find Major Helzephron out."

I never saw a man in such deadly fear. His face went the colour of cheese, and a horrible choking noise began in his throat. He staggered to within a yard of the brink; another step and he would have plunged into the abyss.

"You, you, you!" he said, the last word in a dreadful whisper.

"The Oxford professor—yes. Mr. Vargus, I am a lover of music, and you have entertained me royally to-night. But you have played Chopin for the last time in this world."

I lifted the pistol and covered his heart. His yellow mask quivered and was still. "Quickly, please," he said, and there was even a faint smile of relief about his pallid lips.

He could face death gladly, and I knew why. To have shot him there and cast his body to the void would have been a mercy. I had other uses for Mr. Vargus.

My pistol hand was steady as a rock. With the left I took out Danjuro's handcuffs and walked up to him.

"Not yet," I said, when I was within a foot.

He saw what I meant. As comprehension leapt into his eyes he tried to step back. He nearly did it, but I was just too quick for him. I caught his ankle with the crook of my right foot, and he crashed on his back with his head and shoulders actually over the chasm. Before he could move again I had jerked him backwards by the legs, and had him handcuffed.

I pulled him to his feet by his collar, and half marched, half carried him back into the cave. He was nothing more than a bundle of clothes in my hands.

"Now," I said, "take me at once to the place where Miss Shepherd is confined, and, though I make no promises, it may go less hardly with you than the rest."

He twisted his head and tried to look me in the face. "If I do, will you shoot me?" he whispered, fawning on me like a beaten dog. "For God's sake shoot me, or give me an opportunity to shoot myself."

"The hangman will save you the trouble," I answered brutally. "Now then, march!" He gave a great wail of despair.

"Ah, you don't know what I was once!" he cried, and there was such a horror of remorse, a damnation so profound in that cry of agony, that a fiend would have been moved.

"I heard you play the Third Ballade," I answered, and my voice was no longer firm.

"Death, please, Death."

"Take me quickly to Miss Shepherd. Then perhaps—I can't kill you myself, but ..."

It was as though my words poured a new life into his veins. His knees still knocked together in a loathsome paralysis, but he made effort to shamble forward.