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.

Only Tars Tarkas, Thuvia, and I were left. The fatal marksmanship of the therns had snatched from our companions whatever slender chance they had of gaining the perilous freedom of the world without.

So soon as the last of the gruesome procession had disappeared the girl urged us to take up our flight once more.

She, too, had noted the questioning attitude of the thern who had borne Sator Throg away.

"It bodes no good for us, O Prince," she said. "For even though this fellow dared not chance accusing you in error, there be those above with power sufficient to demand a closer scrutiny, and that, Prince would indeed prove fatal."

I shrugged my shoulders. It seemed that in any event the outcome of our plight must end in death. I was refreshed from my sleep, but still weak from loss of blood. My wounds were painful. No medicinal aid seemed possible. How I longed for the almost miraculous healing power of the strange salves and lotions of the green Martian women. In an hour they would have had me as new.

I was discouraged. Never had a feeling of such utter hopelessness come over me in the face of danger. Then the long flowing, yellow locks of the Holy Thern, caught by some vagrant draught, blew about my face.

Might they not still open the way of freedom? If we acted in time, might we not even yet escape before the general alarm was sounded? We could at least try.

"What will the fellow do first, Thuvia?" I asked. "How long will it be before they may return for us?"

"He will go directly to the Father of Therns, old Matai Shang. He may have to wait for an audience, but since he is very high among the lesser therns, in fact as a thorian among them, it will not be long that Matai Shang will keep him waiting.

"Then if the Father of Therns puts credence in his story, another hour will see the galleries and chambers, the courts and gardens, filled with searchers."

"What we do then must be done within an hour. What is the best way, Thuvia, the shortest way out of this celestial Hades?"

"Straight to the top of the cliffs, Prince," she replied, "and then through the gardens to the inner courts. From there our way will lie within the temples of the therns and across them to the outer court. Then the ramparts--O Prince, it is hopeless. Ten thousand warriors could not hew a way to liberty from out this awful place.

"Since the beginning of time, little by little, stone by stone, have the therns been ever adding to the defences of their stronghold. A continuous line of impregnable fortifications circles the outer slopes of the Mountains of Otz.

"Within the temples that lie behind the ramparts a million fighting-men are ever ready. The courts and gardens are filled with slaves, with women and with children.

"None could go a stone's throw without detection."

"If there is no other way, Thuvia, why dwell upon the difficulties of this. We must face them."

"Can we not better make the attempt after dark?" asked Tars Tarkas. "There would seem to be no chance by day."

"There would be a little better chance by night, but even then the ramparts are well guarded; possibly better than by day. There are fewer abroad in the courts and gardens, though," said Thuvia.

"What is the hour?" I asked.

"It was midnight when you released me from my chains," said Thuvia. "Two hours later we reached the storeroom. There you slept for fourteen hours. It must now be nearly sundown again. Come, we will go to some nearby window in the cliff and make sure."

So saying, she led the way through winding corridors until at a sudden turn we came upon an opening which overlooked the Valley Dor.

At our right the sun was setting, a huge red orb, below the western range of Otz. A little below us stood the Holy Thern on watch upon his balcony. His scarlet robe of office was pulled tightly about him in anticipation of the cold that comes so suddenly with darkness as the sun sets. So rare is the atmosphere of Mars that it absorbs very little heat from the sun. During the daylight hours it is always extremely hot; at night it is intensely cold. Nor does the thin atmosphere refract the sun's rays or diffuse its light as upon Earth. There is no twilight on Mars. When the great orb of day disappears beneath the horizon the effect is precisely as that of the extinguishing of a single lamp within a chamber. From brilliant light you are plunged without warning into utter darkness. Then the moons come; the mysterious, magic moons of Mars, hurtling like monster meteors low across the face of the planet.

The declining sun lighted brilliantly the eastern banks of Korus, the crimson sward, the gorgeous forest. Beneath the trees we saw feeding many herds of plant men. The adults stood aloft upon their toes and their mighty tails, their talons pruning every available leaf and twig. It was then that I understood the careful trimming of the trees which had led me to form the mistaken idea when first I opened my eyes upon the grove that it was the playground of a civilized people.

As we watched, our eyes wandered to the rolling Iss, which issued from the base of the cliffs beneath us. Presently there emerged from the mountain a canoe laden with lost souls from the outer world. There were a dozen of them. All were of the highly civilized and cultured race of red men who are dominant on Mars.

The eyes of the herald upon the balcony beneath us fell upon the doomed party as soon as did ours. He raised his head and leaning far out over the low rail that rimmed his dizzy perch, voiced the shrill, weird wail that called the demons of this hellish place to the attack.

For an instant the brutes stood with stiffly erected ears, then they poured from the grove toward the river's bank, covering the distance with great, ungainly leaps.

The party had landed and was standing on the sward as the awful horde came in sight. There was a brief and futile effort of defence. Then silence as the huge, repulsive shapes covered the bodies of their victims and scores of sucking mouths fastened themselves to the flesh of their prey.

I turned away in disgust.

"Their part is soon over," said Thuvia. "The great white apes get the flesh when the plant men have drained the arteries. Look, they are coming now."

As I turned my eyes in the direction the girl indicated, I saw a dozen of the great white monsters running across the valley toward the river bank. Then the sun went down and darkness that could almost be felt engulfed us.

Thuvia lost no time in leading us toward the corridor which winds back and forth up through the cliffs toward the surface thousands of feet above the level on which we had been.

Twice great banths, wandering loose through the galleries, blocked our progress, but in each instance Thuvia spoke a low word of command and the snarling beasts slunk sullenly away.

"If you can dissolve all our obstacles as easily as you master these fierce brutes I can see no difficulties in our way," I said to the girl, smiling. "How do you do it?"

She laughed, and then shuddered.

"I do not quite know," she said. "When first I came here I angered Sator Throg, because I repulsed him. He ordered me to be thrown into one of the great pits in the inner gardens. It was filled with banths. In my own country I had been accustomed to command. Something in my voice, I do not know what, cowed the beasts as they sprang to attack me.

"Instead of tearing me to pieces, as Sator Throg had desired, they fawned at my feet. So greatly were Sator Throg and his friends amused by the sight that they kept me to train and handle the terrible creatures. I know them all by name. There are many of them wandering through these lower regions. They are the scavengers. Many prisoners die here in their chains. The banths solve the problem of sanitation, at least in this respect.

"In the gardens and temples above they are kept in pits. The therns fear them. It is because of the banths that they seldom venture below ground except as their duties call them."

An idea occurred to me, suggested by what Thuvia had just said.

"Why not take a number of banths and set them loose before us above ground?" I asked.

Thuvia laughed.

"It would distract attention from us, I am sure," she said.

She commenced calling in a low singsong voice that was half purr. She continued this as we wound our tedious way through the maze of subterranean passages and chambers.

Presently soft, padded feet sounded close behind us, and as I turned I saw a pair of great, green eyes shining in the dark shadows at our rear. From a diverging tunnel a sinuous, tawny form crept stealthily toward us.

Low growls and angry snarls assailed our ears on every side as we hastened on and one by one the ferocious creatures answered the call of their mistress.

She spoke a word to each as it joined us. Like well- schooled terriers, they paced the corridors with us, but I could not help but note the lathering jowls, nor the hungry expressions with which they eyed Tars Tarkas and myself.

Soon we were entirely surrounded by some fifty of the brutes. Two walked close on either side of Thuvia, as guards might walk. The sleek sides of others now and then touched my own naked limbs. It was a strange experience; the almost noiseless passage of naked human feet and padded paws; the golden walls splashed with precious stones; the dim light cast by the tiny radium bulbs set at considerable distances along the roof; the huge, maned beasts of prey crowding with low growls about us; the mighty green warrior towering high above us all; myself crowned with the priceless diadem of a Holy Thern; and leading the procession the beautiful girl, Thuvia.

I shall not soon forget it.

Presently we approached a great chamber more brightly lighted than the corridors. Thuvia halted us. Quietly she stole toward the entrance and glanced within. Then she motioned us to follow her.

The room was filled with specimens of the strange beings that inhabit this underworld; a heterogeneous collection of hybrids--the offspring of the prisoners from the outside world; red and green Martians and the white race of therns.

Constant confinement below ground had wrought odd freaks upon their skins. They more resemble corpses than living beings. Many are deformed, others maimed, while the majority, Thuvia explained, are sightless.

As they lay sprawled about the floor, sometimes overlapping one another, again in heaps of several bodies, they suggested instantly to me the grotesque illustrations that I had seen in copies of Dante's INFERNO, and what more fitting comparison? Was this not indeed a veritable hell, peopled by lost souls, dead and damned beyond all hope?

Picking our way carefully we threaded a winding path across the chamber, the great banths sniffing hungrily at the tempting prey spread before them in such tantalizing and defenceless profusion.

Several times we passed the entrances to other chambers similarly peopled, and twice again we were compelled to cross directly through them. In others were chained prisoners and beasts.

"Why is it that we see no therns?" I asked of Thuvia.

"They seldom traverse the underworld at night, for then it is that the great banths prowl the dim corridors seeking their prey. The therns fear the awful denizens of this cruel and hopeless world that they have fostered and allowed to grow beneath their feet. The prisoners even sometimes turn upon them and rend them. The thern can never tell from what dark shadow an assassin may spring upon his back.

"By day it is different. Then the corridors and chambers are filled with guards passing to and fro; slaves from the temples above come by hundreds to the granaries and storerooms. All is life then. You did not see it because I led you not in the beaten tracks, but through roundabout passages seldom used. Yet it is possible that we may meet a thern even yet. They do occasionally find it necessary to come here after the sun has set. Because of this I have moved with such great caution."

But we reached the upper galleries without detection and presently Thuvia halted us at the foot of a short, steep ascent.

"Above us," she said, "is a doorway which opens on to the inner gardens. I have brought you thus far. From here on for four miles to the outer ramparts our way will be beset by countless dangers. Guards patrol the courts, the temples, the gardens. Every inch of the ramparts themselves is beneath the eye of a sentry."

I could not understand the necessity for such an enormous force of armed men about a spot so surrounded by mystery and superstition that not a soul upon Barsoom would have dared to approach it even had they known its exact location. I questioned Thuvia, asking her what enemies the therns could fear in their impregnable fortress.

We had reached the doorway now and Thuvia was opening it.

"They fear the black pirates of Barsoom, O Prince," she said, "from whom may our first ancestors preserve us."

The door swung open; the smell of growing things greeted my nostrils; the cool night air blew against my cheek. The great banths sniffed the unfamiliar odours, and then with a rush they broke past us with low growls, swarming across the gardens beneath the lurid light of the nearer moon.

Suddenly a great cry arose from the roofs of the temples; a cry of alarm and warning that, taken up from point to point, ran off to the east and to the west, from temple, court, and rampart, until it sounded as a dim echo in the distance.

The great Thark's long-sword leaped from its scabbard; Thuvia shrank shuddering to my side.