Our destination, Thuvia said, was a distant storeroom where arms and ammunition in plenty might be found. From there she was to lead us to the summit of the cliffs, from where it would require both wondrous wit and mighty fighting to win our way through the very heart of the stronghold of the Holy Therns to the world without.

"And even then, O Prince," she cried, "the arm of the Holy Thern is long. It reaches to every nation of Barsoom. His secret temples are hidden in the heart of every community. Wherever we go should we escape we shall find that word of our coming has preceded us, and death awaits us before we may pollute the air with our blasphemies."

We had proceeded for possibly an hour without serious interruption, and Thuvia had just whispered to me that we were approaching our first destination, when on entering a great chamber we came upon a man, evidently a thern.

He wore in addition to his leathern trappings and jewelled ornaments a great circlet of gold about his brow in the exact centre of which was set an immense stone, the exact counterpart of that which I had seen upon the breast of the little old man at the atmosphere plant nearly twenty years before.

It is the one priceless jewel of Barsoom. Only two are known to exist, and these were worn as the insignia of their rank and position by the two old men in whose charge was placed the operation of the great engines which pump the artificial atmosphere to all parts of Mars from the huge atmosphere plant, the secret to whose mighty portals placed in my possession the ability to save from immediate extinction the life of a whole world.

The stone worn by the thern who confronted us was of about the same size as that which I had seen before; an inch in diameter I should say. It scintillated nine different and distinct rays; the seven primary colours of our earthly prism and the two rays which are unknown upon Earth, but whose wondrous beauty is indescribable.

As the thern saw us his eyes narrowed to two nasty slits.

"Stop!" he cried. "What means this, Thuvia?"

For answer the girl raised her revolver and fired point-blank at him. Without a sound he sank to the earth, dead.

"Beast!" she hissed. "After all these years I am at last revenged."

Then as she turned toward me, evidently with a word of explanation on her lips, her eyes suddenly widened as they rested upon me, and with a little exclamation she started toward me.

"O Prince," she cried, "Fate is indeed kind to us. The way is still difficult, but through this vile thing upon the floor we may yet win to the outer world. Notest thou not the remarkable resemblance between this Holy Thern and thyself?"

The man was indeed of my precise stature, nor were his eyes and features unlike mine; but his hair was a mass of flowing yellow locks, like those of the two I had killed, while mine is black and close cropped.

"What of the resemblance?" I asked the girl Thuvia. "Do you wish me with my black, short hair to pose as a yellow-haired priest of this infernal cult?"

She smiled, and for answer approached the body of the man she had slain, and kneeling beside it removed the circlet of gold from the forehead, and then to my utter amazement lifted the entire scalp bodily from the corpse's head.

Rising, she advanced to my side and placing the yellow wig over my black hair, crowned me with the golden circlet set with the magnificent gem.

"Now don his harness, Prince," she said, "and you may pass where you will in the realms of the therns, for Sator Throg was a Holy Thern of the Tenth Cycle, and mighty among his kind."

As I stooped to the dead man to do her bidding I noted that not a hair grew upon his head, which was quite as bald as an egg.

"They are all thus from birth," explained Thuvia noting my surprise. "The race from which they sprang were crowned with a luxuriant growth of golden hair, but for many ages the present race has been entirely bald. The wig, however, has come to be a part of their apparel, and so important a part do they consider it that it is cause for the deepest disgrace were a thern to appear in public without it."

In another moment I stood garbed in the habiliments of a Holy Thern.

At Thuvia's suggestion two of the released prisoners bore the body of the dead thern upon their shoulders with us as we continued our journey toward the storeroom, which we reached without further mishap.

Here the keys which Thuvia bore from the dead thern of the prison vault were the means of giving us immediate entrance to the chamber, and very quickly we were thoroughly outfitted with arms and ammunition.

By this time I was so thoroughly fagged out that I could go no further, so I threw myself upon the floor, bidding Tars Tarkas to do likewise, and cautioning two of the released prisoners to keep careful watch. In an instant I was asleep.

How long I slept upon the floor of the storeroom I do not know, but it must have been many hours.

I was awakened with a start by cries of alarm, and scarce were my eyes opened, nor had I yet sufficiently collected my wits to quite realize where I was, when a fusillade of shots rang out, reverberating through the subterranean corridors in a series of deafening echoes.

In an instant I was upon my feet. A dozen lesser therns confronted us from a large doorway at the opposite end of the storeroom from which we had entered. About me lay the bodies of my companions, with the exception of Thuvia and Tars Tarkas, who, like myself, had been asleep upon the floor and thus escaped the first raking fire.

As I gained my feet the therns lowered their wicked rifles, their faces distorted in mingled chagrin, consternation, and alarm.

Instantly I rose to the occasion.

"What means this?" I cried in tones of fierce anger. "Is Sator Throg to be murdered by his own vassals?"

"Have mercy, O Master of the Tenth Cycle!" cried one of the fellows, while the others edged toward the doorway as though to attempt a surreptitious escape from the presence of the mighty one.

"Ask them their mission here," whispered Thuvia at my elbow.

"What do you here, fellows?" I cried.

"Two from the outer world are at large within the dominions of the therns. We sought them at the command of the Father of Therns. One was white with black hair, the other a huge green warrior," and here the fellow cast a suspicious glance toward Tars Tarkas.

"Here, then, is one of them," spoke Thuvia, indicating the Thark, "and if you will look upon this dead man by the door perhaps you will recognize the other. It was left for Sator Throg and his poor slaves to accomplish what the lesser therns of the guard were unable to do-we have killed one and captured the other; for this had Sator Throg given us our liberty. And now in your stupidity have you come and killed all but myself, and like to have killed the mighty Sator Throg himself."

The men looked very sheepish and very scared.

"Had they not better throw these bodies to the plant men and then return to their quarters, O Mighty One?" asked Thuvia of me.

"Yes; do as Thuvia bids you," I said.

As the men picked up the bodies I noticed that the one who stooped to gather up the late Sator Throg started as his closer scrutiny fell upon the upturned face, and then the fellow stole a furtive, sneaking glance in my direction from the corner of his eye.

That he suspicioned something of the truth I could have sworn; but that it was only a suspicion which he did not dare voice was evidenced by his silence.

Again, as he bore the body from the room, he shot a quick but searching glance toward me, and then his eyes fell once more upon the bald and shiny dome of the dead man in his arms. The last fleeting glimpse that I obtained of his profile as he passed from my sight without the chamber revealed a cunning smile of triumph upon his lips.