A second lieutenant spotted the S.O.S. within half an hour of the
films' return. There was an immediate and intense conference. The
lengths of shadows were measured. The size and slope and probable
condition of the clearing's surface were estimated.

A very light plane, intended for artillery-spotting, took off from the
nearest airfield to Boulder Lake.

And Lockley and Jill heard it long before it came in sight. It flew
low, threading its way among valleys and past mountain-flanks to avoid
being spotted against the sky. The two beside the clearing heard it
first as a faint mutter. The sound increased, diminished, then
increased again.

It shot over a minor mountain-flank and surveyed the bare space with
the huge letters on it. Lockley and Jill raced out into view, waving
frantically. The plane circled and circled, estimating the landing
conditions. It swung away to arrive at a satisfactory approach path.

It wavered. It made a half-wingover, and it side-slipped crazily, and
came up and stalled and flipped on its back and dived....

And it came out of its insane antics barely twenty feet above the
ground. It raced away as close as possible to touching its wheels to
earth. It went away behind the mountains. The sound of its going
dwindled and dwindled and was gone. It appeared to have escaped from a
deliberately set trap.

Lockley stared after it. Then he went white.

"Idiot!" he cried fiercely. "Come on! Run!"

He seized Jill's hand. They fled together. Evidently, something had
played upon the pilot of the light plane. He'd been deafened and
blinded and all his senses were a shrieking tumult while his muscles
knotted and his hands froze on the controls of his ship. He hadn't
flown out of the beam that made him helpless. He'd fallen out of it.
And then he raced for the horizon. He got away. And it would appear to
those to whom he reported that he'd arrived too late at the
distress-signal. If fugitives had made it, they'd been overtaken and
captured by the creatures of Boulder Lake, and there'd been an ambush
set up for the plane. It was a reasonable decision.

But it puzzled the pilot's superior officers that he hadn't been
allowed to land the plane before the beam was turned on him. He could
have been paralyzed while on the ground, and he and his plane could
have yielded considerable information to creatures from another world.
It was puzzling.

Lockley and Jill raced for the woodland at the clearing's ed