nothing weird or mysterious about it; a sound that was
essentially earthly, material, modern, the distant purr of a high-powered
automobile on the trail away to their right. Starr turned his face that
way, listening as the horse listened. It seemed to Helen May as though he
had become again earthy and material and modern, with the desert love
song but the fading memory of a dream. He listened, and she received the
impression that something more than idle curiosity held him intent upon
the sound.

The purring persisted, lessened, grew louder again. Starr still looked
that way, listening intently. The machine swept nearer, so that the clear
night air carried the sounds distinctly to where they stood. Starr even
caught the humming of the rear gears and knew that only now and then does
a machine have that peculiar, droning hum; Starr studied it, tried to
impress the sound upon his memory.

The trail looped around the head of a sandy draw and wound over the crest
of a low ridge before it straightened out for a three-mile level run in
the direction of San Bonito, miles away. In walking, Starr had cut
straight across that gully and the loop, so that they had crossed the
trail twice in their journey thus far, and were still within half a mile
of the head of the loop. They should have been able to see the lights, or
at least the reflection of them on the ridge when they came to the draw.
But there was no bright path on sky or earth.

They heard the car ease down the hill, heard the grind of the gears as
the driver shifted to the intermediate for the climb that came after.
They heard the chug of the engine taking the steep grade. Then they
should have caught the white glare of the headlights as the car topped
the ridge. Starr knew that nothing obstructed the view, that in daylight
they could have seen the yellow-brown ribbon of trail where it curved
over the ridge. The machine was coming directly toward them for a short
distance, but there was no light whatever. Starr knew then that whoever
they were, they were running without lights.

"Well, I guess we'd better be ambling along," he said casually, when the
automobile had purred its way beyond hearing. "It's three or four miles
yet, and you're tired."

"Not so much." Helen May's voice was a little lower than usual, but that
was the only sign she gave of any recent deep emotion. "I'd as soon walk
awhile and let you ride." She shrank now from the thought of both riding.

"Wh