failed to reach them over the soft pounding of the ponies' hoofs
on the prairie sod, but suddenly the distant crackling of a half dozen
shots pierced the silence, and their eyes caught the sparkle of the
discharges, winking like fireflies in the night. Before they could
draw up their mounts, the fusillade had ended, and all beneath them was
unbroken gloom.

"Must be rushing the rock," commented Westcott.

"More likely saw something and blazed away at it, just as they did at
that log," and Brennan laughed. "Anyhow they haven't discovered we
have vanished yet. With an hour more we'll be where trails are
unknown."

"In the desert?"

"That is the only safe hiding place around here. Besides we're
carrying a message to Mendez."

"Without the slightest knowledge of where that party is."

"Well, hardly that, Jim. I may not know exactly, but I've got a
glimmer of a notion about where the cuss hangs out, an' I'm going to
have a hunt for it. There's five thousand dollars posted down in
Arizona for that fellow, dead or alive; an' I need the money. Besides,
I reckon this yere Miss Donovan, an' yer ol' partner--what's his
name?--sure, Cavendish--will be mighty glad to see us. You're game for
a try, ain't yer?"

"I shall never stop until I do find them, Dan," said the other
earnestly, the very tone of his voice carrying conviction. "Every cent
of reward is yours; it will be satisfaction enough for me to know those
two are safe."

"That's how I figured it. Now let's trot on; we ain't gaining nothing
by sittin' our saddles here. We can talk while we travel."

There was a few moments of silence, both men evidently busied with
their thoughts; then Westcott asked:

"What is your idea, Dan?"

The marshal rode steadily, humped up over his saddle-horn, his eyes on
the uncertainties in front.

"I ain't really got none," he admitted doggedly, "less it be a blind
trust in Divine Providence; still I got a medium strong grip on a few
things. That Capley girl told you that Matt Moore drove out on the
ridge road?"

"Yes; I asked her about that twice."

"Well, he likely was headed for this yere Sunken Valley. That's point
number one. But he never followed the ridge road very far, for it
skirts the desert. He must have turned off south--but where?"

"Near the lone cottonwood is my guess."

"Why?"

"Because there is a swale there of hard sand, which is easily followed,
and leaves no trail. On either side for mil