As he continued trailing the two he was at first surprised to discover the fidelity with which Nadara had clung to his old trail, and because of this fact he often was able to save miles at a time by taking cross-cuts where, on his way in, he had made wide detours. But at last on the third day, when he attempted this at a place which would have saved him fully ten miles, he was dismayed by the discovery that he could not again pick up either Nadara's trail or that of the cave man. Even his own old trail was entirely obliterated. It was this fact which caused him the greatest concern, for it meant that if Nadara really had been following it she must now be wandering rather aimlessly, possibly in an attempt to again locate it. In which event her speed would be materially reduced, and the probability of her capture by Flatfoot much enhanced. It was possible, too, that the beast already had overtaken her--this, in fact, might be the true cause of the cessation of the pursuit along the way which it had proceeded up to this point. The thought sent Waldo back along his former route, which he was able to follow by recollection, though the spoor was seldom visible. He came upon no sign of those he sought that day, but the next morning he found the point at which Nadara had lost his old trail upon a rocky ridge. The girl evidently assumed that it would lead into the valley below where she might pick it up again in the soft earth, and so her footprints led down a shelving bluff, while plain above them showed the huge imprints of Flatfoot. Up to this point at least he had not caught up with her. Waldo breathed a sigh of relief at the discovery. The trail was at least two days old, for Nadara and Flatfoot had traveled much more rapidly than the wounded man who haunted their footsteps like a grim shadow. About noon Waldo came to a little stream at which both those who preceded him had evidently stopped to drink--he could see where they had knelt in the soft grass at the water's edge. As Waldo stopped to quench his own thirst his eyes rested for an instant upon the farther bank, which at that point was little more than ten feet from him. He saw that the opposite shore was less grassy, and that it sloped down to the water, forming a muddy beach partially submerged. But what riveted his attention were several deep imprints in the mud. He could not be certain, of course, at that distance, but he was sure enough that he had recognized them to cause him to leap to his feet, forgetful of his thirst, and plunge through the stream for a closer inspection. As he bent to examine the spoor at close range he could scarce repress a cry of exultation--they had been made by the hands and knees of Nadara as she had stooped to drink at the very spot not twenty-four hours before.