; and several of them, fitted with claws and racks for transporting
booty, were heavily laden now with metal plates and girders carved from
some larger machine, a roll of caterpillar tread, a slightly bent
axle.... The last pygmy in line, whose afterbody was a bloated tank,
gurgled as it jolted by, and trailed an aroma of looted fuel.

A few yards beyond the staring watchers, each of the little plunderers
pivoted sharply in its turn and without even slackening speed vanished
straight into the cliff-face. Dworn and Qanya looked incredulously at
one another.

"A tunnel!" Dworn grunted in realization.

That explained one mystery, at least--how, if the winged and wingless
strangers' home base was somewhere above the cliffs, the wheeled
machines contrived to forage at the foot of the Barrier. They must have
one or more inclined tunnels, bored through solid rock for a distance
that staggered Dworn's imagination. Emerging at this level, they had
found or constructed a passable road the rest of the way to the valley
floor.... Now he noticed that the ledge to which the spider had so
laboriously climbed showed signs of being an often-used trail, and the
cliffs it skirted exhibited in places the raw marks of recent blasting.

"Remember this spot," he told Qanya. "If we should return this same
way--there's evidently an easier path down."

She said nothing. Dworn wondered wrily if, in her drug beclouded mind,
she was aware of how unlikely it was that either of them would be
returning from beyond the Barrier.

A mad enterprise indeed--a ghost and a zombie, going to seek out a foe
whose numbers and whose might grew ever more apparent. The tunnel
opening here was clear evidence of engineering resources and skill far
beyond that of any of the machine races Dworn knew.

Its discovery was no help to them, since it was far too small to admit
the spider.

"Go on!" Dworn ordered doggedly. "At least we know now that _their_
dwelling can't be far!"

Qanya glanced briefly sidelong at him, then moved the levers, and the
spider rocked upright once more and began to climb.

* * * * *

The sun was low, and the shadows of rocks and dunes in the valley behind
them were pointing long blue fingers eastward, when the machine
staggered up the last precipitous ascent and stood on level ground at
the summit.

Dworn took a deep breath and looked ahead, looked for the first time in
his life upon the unknown land