He ran until he was exhausted; walked for a little while his legs gathered more strength, and his laboring lungs more air; and then ran again. As the minutes passed, the thunder lessened rapidly into a muffled drone; and by the time Phil had panted up to the brink of the hole that gaped where but a little time before the sphere was standing, it had become but a distant purr. He leaned far over and peered into the hot blackness below, but could see nothing. Phil knelt there silently for some minutes, shocked by his strange attack, bewildered by the unexpected descent of the borer. For a time his mind would not work; he had no idea what to do. But gradually his thoughts came to order and made certain things clear. He had been deliberately ambushed. Only by luck had he escaped, he told himself. If it hadn't been for the water jug, he'd now be out of the picture. And on the heels of the ambush had came the surprising descent of the earth-borer. The two incidents coincided too well: the same mind had planned them. And two, men, at least, were in on the plot.... It suddenly became very clear to him that the answer to the puzzle lay with the man who had ambushed him. He would have to get that man. Track him down. Phil acted with decision. He got to his feet and strode rapidly to the deserted Guinness shack, horribly quiet and lonely now in the bright moonlight. In a minute he emerged with a flashlight at his belt and a rifle across his arm. Once again he went over to the new black hole in the desert and looked down. From far below still came the purr, now fainter than ever. His friend, the girl he loved, were down there, he reflected bitterly, and he was helpless to reach them. Well, there was one thing he could do--go man-hunting. Turning, he started off at a long lope for the water-hole. * * * * * Ten minutes later he was there, and off to the side he found the marks of their scuffle--and small black blotches that could be nothing but blood. The other was wounded: could probably not get far. But he might still have his gun, so Phil kept his rifle handy, and tempered his impatience with caution as he set out on the trail of the widely spaced footprints. They led off towards the nearby hills, and in the bright moonlight Phil did not use his flashlight at all, except to investigate other round black blotches that made a line parallel to the prints. As he went on he found his quarry's steps coming more closely together: becoming erratic. Soon they showed as painful drags in the sand, a laborious hauling of one foot after the other.... Phil put away his light and advanced very cautiously.