The trail led around a rocky promontory into a deep and somber gorge. Up the center of this it followed the course of a rapid brook, leaping downward toward the sea. From time to time the man had evidently essayed to scale the cliffs, first upon one side and then upon the other, but each time he had abandoned the attempt before the difficulties and dangers of the precipitous crags.

To Nu the ascent would have proved a simple matter, and so he wondered why the man had turned back each time after clambering but a short distance from the base of the cliffs; but Tur was not a cliff dweller. His peoples had come from a great, level river valley beside the sea—from a country where cliffs and natural caves were the exception rather than the rule, so he had had but little practice in climbing of that sort.

Finally, at the head of the ravine, he had been forced to climb or retrace his steps, and here, at last, he had managed to clamber out upon the table land that stretched beyond the summit. Across this the trail led, turning suddenly toward the west at the edge of another ravine. The abruptness with which the spoor wheeled to the right indicated to Nu that something had suddenly attracted the man's attention toward the new direction and that he had proceeded at a rapid run to investigate. Could he here have discovered the woman he sought? Was he already in pursuit of Nat-ul?—if it was, indeed, she. Was he even now in possession of her?

Nu, too, wheeled to the west and raced rapidly along the well-marked trail. Since he had come upon the signs of Tur, Nu's speed had been infinitely greater than that of the Boat Builder. This his woodcraft told him, so he knew that he was constantly gaining upon the man who was still unconscious of the fact that he was being pursued.

Down the steep side of the ravine Tur must have slid and rolled in a most reckless fashion. At the bottom was a dense forest through which the trail led back toward the sea, after the man had made a series of frantic but futile attempts to scale the opposite heights.

What had he seen or heard or followed that had led him to make such desperate attempts to gain the opposite summit? Should Nu follow him down the ravine, or clamber to the vantage point the other had been unable to reach?

For an instant the troglodyte hesitated. Then he wheeled toward the cliff, and with the agility of long practice backed by ages of cliff dwelling forebears he clambered rapidly upward. At times he was forced to leap for a projecting rock above his head, dangling out over space as he drew himself, by mighty biceps and forearm, to the tiny foothold it afforded. Again, a gnarled root or a small crevice aided him in his ascent, until presently he crawled over the brow and stood erect once more on level ground.

Nu looked about, warily—there was no sign of the man or the woman. Then he examined the ground in ever enlarging circles, but no spoor such as he sought rewarded his eager eyes.

He had about decided to return to the bottom of the ravine and follow Tur's spoor when, clear and shrill from the west, there came to his ears the scream of a woman in distress.

And scarce had its first note risen upon the air than Nu, the son of Nu, was dashing madly in the direction of the sound.