sand car. Brion
ground it fiercely around and turned the headlights on the tracks.
There were the marks of a sand car's treads, half obscured by thin,
unmarked wheel tracks. He turned off the lights and forced himself
to move slowly and to do an accurate job. A quick glimpse at his
watch showed him there were four hours left to go. The moonlight was
bright enough to illuminate the tracks. Driving with one hand, he
turned on the radio transmitter, already set for Krafft's wave
length.

When the operator acknowledged his signal Brion reported what they
had discovered and his conclusions. "Get that message to Commander
Krafft now. I can't wait to talk to him--I'm following the tracks."
He killed the transmission and stamped on the accelerator. The sand
car churned and bounced down the track.

"They are going to the mountains," Ulv said some time later, as the
tracks still pointed straight ahead. "There are caves there and many
magter have been seen near them; that is what I have heard."

The guess was correct. Before nine o'clock the ground humped into a
range of foothills, and the darker masses of mountains could be seen
behind them, rising up to obscure the stars.

"Stop the car here," Ulv said, "The caves begin not too far ahead.
There may be magter watching or listening, so we must go quietly."

Brion followed the deep-cut grooves, carrying the radio. Ulv came
and went on both sides, silently as a shadow, scouting for hidden
watchers. As far as he could discover there were none.

By nine-thirty Brion realized they had deserted the sand car too
soon. The tracks wound on and on, and seemed to have no end. They
passed some caves which Ulv pointed out to him, but the tracks never
stopped. Time was running out and the nightmare stumbling through
the darkness continued.

"More caves ahead," Ulv said, "Go quietly."

They came cautiously to the crest of a hill, as they had done so
many times already, and looked into the shallow valley beyond. Sand
covered the valley floor, and the light of the setting moon shone
over the tracks at a flat angle, marking them off sharply as lines
of shadow. They ran straight across the sandy valley and disappeared
into the dark mouth of a cave on the far side.

Sinking back behind the hilltop, Brion covered the pilot light with
his hand and turned on the transmitter. Ulv stayed above him,
staring at the opening of the cave.

"This is an important message," Brion whispered into the m