Even as he spoke, that faint humming, throbbing sound again filled the air. "Look there! See it, Bill?" "I see it." What I saw was an agitation, slight but unmistakable, in the thicket from which we had emerged but a few moments before. Something was moving there, something was gliding through the dense undergrowth. I jerked out my revolver. Rhodes had already drawn his. "Might as well try a shot," said he, "for it won't show itself, in all likelihood, while we are standing ready to receive it." We fired almost simultaneously. There was a smothered crash in the thicket, as though some heavy body had given a powerful lurch sideways. The throbbing of that mysterious sound grew faster, louder; the agitated foliage began to shake and quiver violently; and then of a sudden sound and agitation were stilled. "We got it, Bill!" cried Milton, starting towards the spot. "For Heaven's sake," I called after him, "don't go over there! Let's get out of this. It may not be dead, and--and we have no idea what in the world the thing is." "We'll find that out." I suppose that I should have been going along after him the next moment, but Drorathusa sprang forward with a cry of horror, began tugging at his sleeve and begging him to come back. So earnest was her manner, so great the fear shown by this woman usually so self-contained and emotionless, Rhodes gave in, though with great apparent reluctance. A few moments, and we were moving away from the spot. This Rhodes has always regretted, for to this day we do not know for certain what that thing was which followed us for so long. I have regretted it more than once myself; but I confess that I had no regrets at the time. I say we do not know for certain: we do know what Drorathusa and the others thought that it was; but that is a creature so grisly that it must (at any rate, such is the belief of Rhodes and myself) be placed amongst Chimeras, Hydras and such fabled monsters. At length, after a long and fatiguing march, we reached the spot where the water goes plunging over a tremendous precipice. The falls are perpendicular, their height at least half a thousand feet. It was necessary to move off to the right for a considerable distance to find a way of descent. The bottom reached, we headed for the stream. There we found the boat which the Dromans had left in their outward journey, and beside it was a second and smaller one. This strange craft was something of a mystery to our Hypogeans; but Drorathusa found a message, traced on the inner surface of a piece of bark, and that seemed to clarify the matter somewhat. Drorathusa held up three fingers; three men had come in that boat. And one of them, she told us, must have been the man whose body we had found hanging in the tentacle of the octopus. What had become of the victim's companions? Why had the trio come into a place so dreadful? Well, why had we?