As the ascents and descents became more frequent, a new terror began to take possession of him—what if there were a hole in the floor, and he should go slipping down into bottomless vacancy? Once, with this fear foremost in his mind, he actually did slip, and, with a horrified scream, found himself falling into space! But he did not have far to go—there was a splash, and unseen waters closed over him. For an instant he floundered wildly in the cold depths, drinking in huge gulps while his bewildered mind vaguely apprehended that the end had come; then, groping by instinct, he found his way shoreward, grasped at an overhanging rock and pulled himself to comparative safety, while all about him the echoes of his sputtering and splashing sounded like the mutterings of evil spirits.

After this ordeal, Ru moved even more cautiously than before. To his mind it was not credible that he had slipped by natural means—the simple explanation was that some invisible watcher had shoved him into the waters. New panic seized him as he wondered how to elude the attacks of his silent persecutor; and it was long before he could summon forth the courage to venture on into the unknown.

Yet he had no choice; and for a time that seemed never-ending and a distance that seemed interminable, he groped through the blackness of the winding mazes. The only sound was the occasional murmuring of invisible waters, varied by the unearthly echoes of his soft footsteps or of his voice when he called to Wuff. For all he could tell, he might not have moved an inch since entering the cavern—in this lightless world, space seemed to have been blotted out.

At last, in utter despair that matched his utter exhaustion, Ru flung himself down upon the cave floor for a few hours' rest. It may be that in that hazy interval he found needed repose—certainly, he was long in a state of half-consciousness, in which confused visions trailed across his mind. First he would see an avenging demon with eyes like fire and a club as big as a mountain and an evil, sneering face like Grumgra's; then he would view a dark gallery from which a wolf the size of a bison would emerge, with long sharp teeth and blood-dripping tongue; then the scene would change and there would be a murmuring of soft voices, and he would feel the hands of Yonyo and peer into her sparkling eyes, and all things would grow comforting and kindly; then once more he would be alone in the darkness, and all about him would brood slinking demons with snaky arms, and vulturelike birds with wings wide as a spreading tree, and enormous bears into whose cavernous jaws he was forced to walk....

From one such nightmare he was aroused with the consciousness that many hours had passed. Perhaps in the world above ground another day had broken—but here all was unchanged. At his side he could hear the rhythmic breathing of the invisible Wuff; but, except for that faint murmuring, the silence was undisturbed; and through the pitchy darkness there was still not a spark to be seen.

But now Ru was aware of a new and most unwelcome sensation, an emptiness within him that brought dreadful premonitions—the gnawings of incipient hunger. In a flash of terrible insight, he perceived that here was a foe more destructive even than the unknown horrors of the dark. What if he should be a captive for days within the cave, captive not only without food but without the means of finding food? In old times of famine he had known starvation and learned what a savage thing it may be; but never had he imagined so dire a fate as to starve in the darkness, with only a wolf for companion!

And as Ru recalled that his companion was a wolf, curious and horrible fancies flitted through his mind. What if, goaded to madness by the hunger pain, he should be plunged into a life-or-death struggle with Wuff—yes, even with Wuff, his protector and his friend? What if, in a fury of self-preservation, he should be tempted to slay Wuff for food?—or if Wuff, reduced to the ferocity of his kind, should pounce upon his master with murderous, slashing fangs?

So appalling did these possibilities seem, and so far from remote, that Ru could retain his sanity only by thrusting them resolutely from his mind. Springing suddenly to his feet, he called to Wuff, then set off once more down the lonely galleries at as determined a pace as the darkness would permit.

The hours went by, and still he wound around interminable curves—and still there was no relief in sight. His hunger had risen to the point of torment, his fatigue to the point of anguish; but there was nothing to do except to go on and on, on and on, lest the fate he dreaded should overtake him. His anxiety was all the greater because of the strange manner of Wuff; at times the beast panted heavily, at times whined in low complaint, at times querulously grumbled and growled, while once or twice—with a display of evil temper he had never shown before—he snapped angrily at Ru's hand.

It was after Ru had renounced his last hope that he beheld the first encouraging sign. Like one wearily trudging on the way to foreordained doom, he was plodding mechanically along the labyrinths, in such torment of mind and body that he had almost ceased to dream of escape—when suddenly, rounding a sharp turn, he was confronted by that which made him pause in mingled joy and alarm.