Clear to the hilt my weapon passed through his body, and with a frightful shriek he sank to the floor, dead.

Halting only for the brief instant that was required to wrench my sword from the carcass of my late antagonist, I sprang across the chamber to the blank wall beyond, through which the thern had attempted to pass. Here I sought for the secret of its lock, but all to no avail.

In despair I tried to force the thing, but the cold, unyielding stone might well have laughed at my futile, puny endeavors. In fact, I could have sworn that I caught the faint suggestion of taunting laughter from beyond the baffling panel.

In disgust I desisted from my useless efforts and stepped to the chamber's single window.

The slopes of Otz and the distant Valley of Lost Souls held nothing to compel my interest then; but, towering far above me, the tower's carved wall riveted my keenest attention.

Somewhere within that massive pile was Dejah Thoris. Above me I could see windows. There, possibly, lay the only way by which I could reach her. The risk was great, but not too great when the fate of a world's most wondrous woman was at stake.

I glanced below. A hundred feet beneath lay jagged granite boulders at the brink of a frightful chasm upon which the tower abutted; and if not upon the boulders, then at the chasm's bottom, lay death, should a foot slip but once, or clutching fingers loose their hold for the fraction of an instant.

But there was no other way and with a shrug, which I must admit was half shudder, I stepped to the window's outer sill and began my perilous ascent.

To my dismay I found that, unlike the ornamentation upon most Heliumetic structures, the edges of the carvings were quite generally rounded, so that at best my every hold was most precarious.

Fifty feet above me commenced a series of projecting cylindrical stones some six inches in diameter. These apparently circled the tower at six-foot intervals, in bands six feet apart; and as each stone cylinder protruded some four or five inches beyond the surface of the other ornamentation, they presented a comparatively easy mode of ascent could I but reach them.

Laboriously I climbed toward them by way of some windows which lay below them, for I hoped that I might find ingress to the tower through one of these, and thence an easier avenue along which to prosecute my search.

At times so slight was my hold upon the rounded surfaces of the carving's edges that a sneeze, a cough, or even a slight gust of wind would have dislodged me and sent me hurtling to the depths below.

But finally I reached a point where my fingers could just clutch the sill of the lowest window, and I was on the point of breathing a sigh of relief when the sound of voices came to me from above through the open window.

"He can never solve the secret of that lock." The voice was Matai Shang's. "Let us proceed to the hangar above that we may be far to the south before he finds another way-should that be possible."

"All things seem possible to that vile calot," replied another voice, which I recognized as Thurid's.

"Then let us haste," said Matai Shang. "But to be doubly sure, I will leave two who shall patrol this runway. Later they may follow us upon another flier-overtaking us at Kaol."

My upstretched fingers never reached the window's sill. At the first sound of the voices I drew back my hand and clung there to my perilous perch, flattened against the perpendicular wall, scarce daring to breathe.

What a horrible position, indeed, in which to be discovered by Thurid! He had but to lean from the window to push me with his sword's point into eternity.

Presently the sound of the voices became fainter, and once again I took up my hazardous ascent, now more difficult, since more circuitous, for I must climb so as to avoid the windows.

Matai Shang's reference to the hangar and the fliers indicated that my destination lay nothing short of the roof of the tower, and toward this seemingly distant goal I set my face.

The most difficult and dangerous part of the journey was accomplished at last, and it was with relief that I felt my fingers close about the lowest of the stone cylinders.

It is true that these projections were too far apart to make the balance of the ascent anything of a sinecure, but I at least had always within my reach a point of safety to which I might cling in case of accident.

Some ten feet below the roof, the wall inclined slightly inward possibly a foot in the last ten feet, and here the climbing was indeed immeasurably easier, so that my fingers soon clutched the eaves.

As I drew my eyes above the level of the tower's top I saw a flier all but ready to rise.

Upon her deck were Matai Shang, Phaidor, Dejah Thoris, Thuvia of Ptarth, and a few thern warriors, while near her was Thurid in the act of clambering aboard.

He was not ten paces from me, facing in the opposite direction; and what cruel freak of fate should have caused him to turn about just as my eyes topped the roof's edge I may not even guess.

But turn he did; and when his eyes met mine his wicked face lighted with a malignant smile as he leaped toward me, where I was hastening to scramble to the secure footing of the roof.

Dejah Thoris must have seen me at the same instant, for she screamed a useless warning just as Thurid's foot, swinging in a mighty kick, landed full in my face.

Like a felled ox, I reeled and tumbled backward over the tower's side.

If there be a fate that is sometimes cruel to me, there surely is a kind and merciful Providence which watches over me.

As I toppled from the tower into the horrid abyss below I counted myself already dead; and Thurid must have done likewise, for he evidently did not even trouble himself to look after me, but must have turned and mounted the waiting flier at once.

Ten feet only I fell, and then a loop of my tough, leathern harness caught upon one of the cylindrical stone projections in the tower's surface-and held. Even when I had ceased to fall I could not believe the miracle that had preserved me from instant death, and for a moment I hung there, cold sweat exuding from every pore of my body.

But when at last I had worked myself back to a firm position I hesitated to ascend, since I could not know that Thurid was not still awaiting me above.

Presently, however, there came to my ears the whirring of the propellers of a flier, and as each moment the sound grew fainter I realized that the party had proceeded toward the south without assuring themselves as to my fate.

Cautiously I retraced my way to the roof, and I must admit that it was with no pleasant sensation that I raised my eyes once more above its edge; but, to my relief, there was no one in sight, and a moment later I stood safely upon its broad surface.

To reach the hangar and drag forth the only other flier which it contained was the work of but an instant; and just as the two thern warriors whom Matai Shang had left to prevent this very contingency emerged upon the roof from the tower's interior, I rose above them with a taunting laugh.

Then I dived rapidly to the inner court where I had last seen Woola, and to my immense relief found the faithful beast still there.

The twelve great banths lay in the doorways of their lairs, eyeing him and growling ominously, but they had not disobeyed Thuvia's injunction; and I thanked the fate that had made her their keeper within the Golden Cliffs, and endowed her with the kind and sympathetic nature that had won the loyalty and affection of these fierce beasts for her.

Woola leaped in frantic joy when he discovered me; and as the flier touched the pavement of the court for a brief instant he bounded to the deck beside me, and in the bearlike manifestation of his exuberant happiness all but caused me to wreck the vessel against the courtyard's rocky wall.