Suddenly he stood before us, as a ghost might do, though whence he came we could not see.  Presently the mystery was explained.  Here in the cliff face there was a cleft, though one invisible even from a few paces away, since its outer edge projected over the inner wall of rock.  Moreover, this opening was not above four feet in width, a mere split in the huge mountain mass caused by some titanic convulsion in past ages.  For it was a definite split since, once entered, far, far above could be traced a faint line of light coming from the sky, although the gloom of the passage was such that torches, which were stored at hand, must be used by those who threaded it.  One man could have held the place against a hundred—­until he was killed.  Still, it was guarded, not only at the mouth where the warrior had appeared, but further along at every turn in the jagged chasm, and these were many.

Into this grim place we went.  The Zulus did not like it at all, for they are a light-loving people and I noted that even Umslopogaas seemed scared and hung back a little.  Nor did Hans, who with his usual suspicion, feared some trap; nor, for the matter of that, did I, though I thought it well to appear much interested.  Only Robertson seemed quite indifferent and trudged along stolidly after a man carrying a torch.

Old Billali put his head out of the litter and shouted back to me to fear nothing, since there were no pitfalls in the path, his voice echoing strangely between those narrow walls of measureless height.

For half an hour or more we pursued this dreary, winding path round the corners of which the draught tore in gusts so fierce that more than once the litters with the wounded men and those who bore them were nearly blown over.  It was safe enough, however, since on either side of us, smooth and without break, rose the sheer walls of rock over which lay the tiny ribbon of blue sky.  At length the cleft widened somewhat and the light grew stronger, making the torches unnecessary.

Then of a sudden we came to its end and found ourselves upon a little plateau in the mountainside.  Behind us for a thousand feet or so rose the sheer rock wall as it did upon the outer face, while in front and beneath, far beneath, was a beautiful plain circular in shape and of great extent, which plain was everywhere surrounded, so far as I could see, by the same wall of rock.  In short, notwithstanding its enormous size, without doubt it was neither more nor less than the crater of a vast extinct volcano.  Lastly, not far from the centre of this plain was what appeared to be a city, since through my glasses I could see great walls built of stone, and what I thought were houses, all of them of a character more substantial than any that I had discovered in the wilds of Africa.

I went to Billali’s litter and asked him who lived in the city.

“No one,” he answered, “it has been dead for thousands of years, but She-who-commands is camped there at present with an army, and thither we go at once.  Forward, bearers.”