ght free from his grip, staggered to his feet and went
reeling away. Phil tore loose from the rope and bounded after him,
never feeling, at the moment, his powder-burned chest.

And then he halted in his tracks.

A great roar came thundering over the desert!

* * * * *

At once he knew that it came from the earth-borer's disintegrators.
The sphere had started down without him.

He stood stock still, petrified with surprise, facing the sound, while
his attacker melted farther and farther into the night. And then,
suddenly, Phil Holmes was sprinting desperately back towards the
Guinness camp.

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.