ited to see who would emerge, but a long
time went by without their catching the slightest sign of life within.
The face of Clee's wrist watch was fluorescing brilliantly now, and
moment by moment the weird glow was increasing. Jim stirred nervously.

"I don't mind telling you, I'm scared," he said.

"Aw, they won't make you walk back," consoled Clee; but he was scared
himself. Why didn't something happen? Why didn't someone come out of
the ship?

Jim thought he heard a noise, and touched Clee on the shoulder,
pointing to a place on the trail down which they had come a few
minutes before. Clee looked, and as he did so the hair on the back of
his neck stood up. For the bushes along the side of the path were
moving as if they were being brushed aside by someone in
passing--someone making a straight line to the spot where they lay
concealed. And no one was there!

"Can they be invisible?" breathed Jim, every pore in his body
prickling.

* * * * *

For a moment the two men could hardly breathe, so great was their
unnamed fear. During that time no other movements could be noted. Then
Clee suddenly pointed to a bush only five yards away. Half a dozen
leaf-tipped branches were bending slowly in their direction--and then
a sharp crack, as of a broken twig, came to them from the same spot.

Panic, blind and unreasoning, swept them. "Run!" gasped Jim; and
together, instinctively, they turned and scrambled down the side of
the ridge to get away, anywhere, far from the approaching menace of
they knew not what. Reckless of possible injury, they slid and
stumbled down the brush-covered slope--and right behind them came
sudden crashing sounds of pursuit.

New fears lent wings to their flight, but the sounds behind continued
inexorably at their heels no matter how fast they ran or how lucky
they were in making past obstacles. Their pursuer was as fast as they.
They had no idea who--or what--it might be, for in the brief glances
they snatched over their shoulders they could not see anything at all!

The going was bad, and the two campers had not gone more than a
quarter-mile when they were breathing hard, and felt that they could
not make one more step without collapsing on the ground to give their
laboring lungs a chance to catch up. Panting like dogs they dragged
themselves along through pine and birch trees, around large rocks and
over briar-covered hills, only a few steps ahead of their purs