When he thrust, however, I was not there, for I had fought with therns before; and while none had ever resorted to precisely that same expedient, I knew them to be the least honorable and most treacherous fighters upon Mars, and so was ever on the alert for some new and devilish subterfuge when I was engaged with one of their race.

But at length he overdid the thing; for, drawing his shortsword, he hurled it, javelinwise, at my body, at the same instant rushing upon me with his long-sword. A single sweeping circle of my own blade caught the flying weapon and hurled it clattering against the far wall, and then, as I sidestepped my antagonist's impetuous rush, I let him have my point full in the stomach as he hurtled by.

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.