e.

One scavenger shuddered with the force of a heavy explosion somewhere
within it, and subsided, smoking. The other too staggered under
crippling impacts, but ground somehow into motion, spinning and sliding
crazily down the gravel slope. Then, as the first attacker's shock-wave
made the very earth tremble, a second and a third plunged from the black
heights, and as the last one rose screeching from its swoop the whole
lower face of the hillside boomed into a holocaust of flame and oily
smoke. The fleeing scavenger was gone, enveloped somewhere in an acre of
fiery hell.

Dworn, two hundred yards away, felt a searing breath of heat, and with
a great effort controlled the impulse to whirl round and race for opener
ground. He sat still, hands cramped sweating on the beetle's controls,
while the sky whistled vindictively with the flight of things that
circled in search of further targets.

When, after a seeming eon, their screaming died away, he released held
breath in a long sigh. He found himself trembling with reaction. Still
he didn't stir. He was ransacking his memory for something he should be
able to recall but which eluded him--a myth, perhaps, heard as a child
beside the campfires of the horde--

The old men would know; Yold would have known. At thought of his father,
the grief and fury rose up again in Dworn, and this time he knew the
object of his vengeful anger. There was small doubt now in his mind that
those flying machines which struck so swiftly and so murderously had
been the beetles' attackers.

But he didn't know what they were. He knew, of course, about the
machines called hornets, which could fly and strike at fearful speeds
like that, outracing sound. But the hornets flew only in daylight, and
made no trouble for the nocturnal race of beetles. These--were something
else.

And more--between the deadly night-fliers and the harmless-looking
aluminum crawlers he had seen, Dworn sensed some connection, some
unnatured symbiosis. He had heard vague rumors about such arrangements,
but had half-discounted them; any of the peoples whom he knew at first
hand would have scorned to enter into alliance with an alien species.

Lastly, he realized bitterly, he didn't even know where the enemy's
lair, their base on the ground, might be....

* * * * *

The moon stood high now. But the Barrier, close at hand now, rose like
an immense black wall, folded in shadows, revealing no