"They are kept to do the bidding of the race of therns; to furnish at once their sport and their sustenance.

"Now and again some hapless pilgrim, drifting out upon the silent sea from the cold Iss, escapes the plant men and the great white apes that guard the Temple of Issus and falls into the remorseless clutches of the therns; or, as was my misfortune, is coveted by the Holy Thern who chances to be upon watch in the balcony above the river where it issues from the bowels of the mountains through the cliffs of gold to empty into the Lost Sea of Korus.

"All who reach the Valley Dor are, by custom, the rightful prey of the plant men and the apes, while their arms and ornaments become the portion of the therns; but if one escapes the terrible denizens of the valley for even a few hours the therns may claim such a one as their own. And again the Holy Thern on watch, should he see a victim he covets, often tramples upon the rights of the unreasoning brutes of the valley and takes his prize by foul means if he cannot gain it by fair.

"It is said that occasionally some deluded victim of Barsoomian superstition will so far escape the clutches of the countless enemies that beset his path from the moment that he emerges from the subterranean passage through which the Iss flows for a thousand miles before it enters the Valley Dor as to reach the very walls of the Temple of Issus; but what fate awaits one there not even the Holy Therns may guess, for who has passed within those gilded walls never has returned to unfold the mysteries they have held since the beginning of time.

"The Temple of Issus is to the therns what the Valley Dor is imagined by the peoples of the outer world to be to them; it is the ultimate haven of peace, refuge, and happiness to which they pass after this life and wherein an eternity of eternities is spent amidst the delights of the flesh which appeal most strongly to this race of mental giants and moral pygmies."

"The Temple of Issus is, I take it, a heaven within a heaven," I said. "Let us hope that there it will be meted to the therns as they have meted it here unto others."

"Who knows?" the girl murmured.

"The therns, I judge from what you have said, are no less mortal than we; and yet have I always heard them spoken of with the utmost awe and reverence by the people of Barsoom, as one might speak of the gods themselves."

"The therns are mortal," she replied. "They die from the same causes as you or I might: those who do not live their allotted span of life, one thousand years, when by the authority of custom they may take their way in happiness through the long tunnel that leads to Issus.

"Those who die before are supposed to spend the balance of their allotted time in the image of a plant man, and it is for this reason that the plant men are held sacred by the therns, since they believe that each of these hideous creatures was formerly a thern."

"And should a plant man die?" I asked.

"Should he die before the expiration of the thousand years from the birth of the thern whose immortality abides within him then the soul passes into a great white ape, but should the ape die short of the exact hour that terminates the thousand years the soul is for ever lost and passes for all eternity into the carcass of the slimy and fearsome silian whose wriggling thousands seethe the silent sea beneath the hurtling moons when the sun has gone and strange shapes walk through the Valley Dor."

"We sent several Holy Therns to the silians to-day, then," said Tars Tarkas, laughing.

"And so will your death be the more terrible when it comes," said the maiden. "And come it will-you cannot escape."

"One has escaped, centuries ago," I reminded her, "and what has been done may be done again."

"It is useless even to try," she answered hopelessly.

"But try we shall," I cried, "and you shall go with us, if you wish."

"To be put to death by mine own people, and render my memory a disgrace to my family and my nation? A Prince of the House of Tardos Mors should know better than to suggest such a thing."

Tars Tarkas listened in silence, but I could feel his eyes riveted upon me and I knew that he awaited my answer as one might listen to the reading of his sentence by the foreman of a jury.

What I advised the girl to do would seal our fate as well, since if I bowed to the inevitable decree of age-old superstition we must all remain and meet our fate in some horrible form within this awful abode of horror and cruelty.

"We have the right to escape if we can," I answered. "Our own moral senses will not be offended if we succeed, for we know that the fabled life of love and peace in the blessed Valley of Dor is a rank and wicked deception. We know that the valley is not sacred; we know that the Holy Therns are not holy; that they are a race of cruel and heartless mortals, knowing no more of the real life to come than we do.

"Not only is it our right to bend every effort to escape-it is a solemn duty from which we should not shrink even though we know that we should be reviled and tortured by our own peoples when we returned to them.

"Only thus may we carry the truth to those without, and though the likelihood of our narrative being given credence is, I grant you, remote, so wedded are mortals to their stupid infatuation for impossible superstitions, we should be craven cowards indeed were we to shirk the plain duty which confronts us.

"Again there is a chance that with the weight of the testimony of several of us the truth of our statements may be accepted, and at least a compromise effected which will result in the dispatching of an expedition of investigation to this hideous mockery of heaven."

Both the girl and the green warrior stood silent in thought for some moments. The former it was who eventually broke the silence.

"Never had I considered the matter in that light before," she said. "Indeed would I give my life a thousand times if I could but save a single soul from the awful life that I have led in this cruel place. Yes, you are right, and I will go with you as far as we can go; but I doubt that we ever shall escape."

I turned an inquiring glance toward the Thark.

"To the gates of Issus, or to the bottom of Korus," spoke the green warrior; "to the snows to the north or to the snows to the south, Tars Tarkas follows where John Carter leads. I have spoken."

"Come, then," I cried, "we must make the start, for we could not be further from escape than we now are in the heart of this mountain and within the four walls of this chamber of death."

"Come, then," said the girl, "but do not flatter yourself that you can find no worse place than this within the territory of the therns."

So saying she swung the secret panel that separated us from the apartment in which I had found her, and we stepped through once more into the presence of the other prisoners.

There were in all ten red Martians, men and women, and when we had briefly explained our plan they decided to join forces with us, though it was evident that it was with some considerable misgivings that they thus tempted fate by opposing an ancient superstition, even though each knew through cruel experience the fallacy of its entire fabric.

Thuvia, the girl whom I had first freed, soon had the others at liberty. Tars Tarkas and I stripped the bodies of the two therns of their weapons, which included swords, daggers, and two revolvers of the curious and deadly type manufactured by the red Martians.

We distributed the weapons as far as they would go among our followers, giving the firearms to two of the women; Thuvia being one so armed.

With the latter as our guide we set off rapidly but cautiously through a maze of passages, crossing great chambers hewn from the solid metal of the cliff, following winding corridors, ascending steep inclines, and now and again concealing ourselves in dark recesses at the sound of approaching footsteps.