As we advanced, the way led from beneath the overhanging cliffs
out into a dim light, and then it was that I saw that the trail
had been cut from the living rock, and that it ran up along the
river's side beyond the rapids.

For hours we followed the dark and gloomy river farther and farther
into the bowels of Mars. From the direction and distance I knew
that we must be well beneath the Valley Dor, and possibly beneath
the Sea of Omean as well--it could not be much farther now to the
Temple of the Sun.

Even as my mind framed the thought, Woola halted suddenly before a
narrow, arched doorway in the cliff by the trail's side. Quickly
he crouched back away from the entrance, at the same time turning
his eyes toward me.

Words could not have more plainly told me that danger of some sort
lay near by, and so I pressed quietly forward to his side, and
passing him looked into the aperture at our right.

Before me was a fair-sized chamber that, from its appointments, I
knew must have at one time been a guardroom. There were racks for
weapons, and slightly raised platforms for the sleeping silks and
furs of the warriors, but now its only occupants were two of the
therns who had been of the party with Thurid and Matai Shang.

The men were in earnest conversation, and from their tones it was
apparent that they were entirely unaware that they had listeners.