The aeroplane whirled and sped away over the rocky table land. Three or four miles of this were covered. Then Mr. Cook ordered Roy to head north again as far as the edge of the ridge and follow this back to the west. Mr. Cook explained what he was doing. When the aeroplane was elevated he at once lost the trail. But, seeing that the supposed fugitive was heading for the plateau, he had hurried forward hoping to get sight of the flying Hassell.

There was no sign of the man where he would naturally have entered the rocks. Nor was there indication of him to the east within the distance he could probably cover, on foot. Mr. Cook was now about to make a similar search to the west. Three or four miles the whirring airship cleaved the breezeless, tonic air to the west. It was after eight o’clock and the strain was beginning to tell on Roy. The car was working perfectly, but an aviator’s nerves never relax. Four or five hours in an aeroplane frequently leave the controller utterly exhausted.

At this point, the fringe of plateaus or buttes ended abruptly in a wide, basin-like valley of sand and alkali. As the aeroplane shot out over this, there was a sharp whistle from Mr. Cook and the instant command: “South again!” Roy altered the swing of his ship, and then made the discovery that had startled his companion. South of the plateaus the strip of desert opened out like a fan, with the wide portion leading to the distant mountain cliffs.

Perhaps a mile ahead, only a black spot on the half white sands of the vacant desert, a moving object could be seen.

“Right over him,” said Mr. Cook quickly.

Roy’s brain was whirling with excitement. Within two minutes, the black object had become a man hastening across the sands toward the high ground. He had heard the engines and propellers and had come to a halt. Although the aeroplane was, perhaps, six hundred feet in the air, it was plain that Mr. Cook’s theory was right. It was Mike Hassell who stood, motionless and as calm, apparently, as if behind Joe’s bar.

“Come down,” was Mr. Cook’s sharp order.

The boy’s heart throbbed. What was about to happen? Neither man had spoken. Would the thief surrender? Or, would it be a tragedy? As the aeroplane touched the sand with a jolt and bumped ahead on its light wheels, Roy felt Mr. Cook drop from the car. When the trembling car at last came to a stop, 300 yards beyond Hassell, the young operator also sprang to the ground. As he turned and caught sight of the two men, he felt cold all over. Something in their attitude told him that the voiceless men facing each other would not speak in words.

Hassell made no attempt to retreat. The white heavy desert stretched about him like a floor. A black hat was pulled low over his eyes. His arms hung limply at his sides. There was not even a revolver in sight. Approaching the murderer-thief was Roy’s employer. His hat was pushed back from his forehead, and, as he strode forward with a slow pace, his arms also hung loosely by his sides.

Roy nervously thought of his new untried revolver and laid his hand upon it. These men were both armed. The boy could see the holster of each hanging at his side. The men were now about a hundred yards from each other. Roy could no longer restrain himself. As Mr. Cook advanced toward the motionless Hassell the boy also began to move forward. Finally, Mr. Cook stopped suddenly. Roy continued to advance until he heard the imperative words: “Go back!” They were from Mr. Cook. But, while he spoke, the man neither moved nor took his eyes from the equally statue-like Hassell. He had heard the boy following.