d to cause him to exhibit such breathless interest,
and all the signs of unusual excitement.

When finally the lad on his knees did look up, Bob saw a grave
expression on his face.

"There's something wrong, Frank; tell me what it is?" he demanded.

"I've made an unpleasant discovery, Bob," replied the other. "Charley!"
he added turning to the wondering Celestial, "go back to our camp, and
bring our guns right away, both of them, see?"

"Yep, bloss, me unelstand. Charley Moi gettee gluns light away quick!"
and as he said this the obliging Chinaman went on a run, his pigtail and
blue blouse flying out behind him.

"Say, whatever does all this mystery mean, Frank?" asked Bob, almost
helplessly.

"Just what you might imagine; that there's danger hanging about us,
Bob."

The eyes of the astonished Bob sought the ground at the point where his
chum had been so deeply interested.

"Then it must be something you just discovered there, and that's a
fact," he declared; "because you didn't act this way three minutes ago."

"I happened to discover footprints coming from another quarter," Frank
went on, calmly; "and they headed into this crevice, just as those of
the moccasined Moqui did from that side. And they came after old
Havasupai had gone up, for I found where they wiped out a part of one of
his tracks."

"Footprints, and were they made by the old professor, do you think?"
asked Bob.

"Not any. Fact is," observed Frank, as though deciding to have the worst
over, "they were the tracks of three persons, all men!"

"Oh! my! three, you said, Frank; and that would mean Eugene, Spanish
Joe, and Abajo, wouldn't it?"

"Just the very ones I meant," replied Frank.

"Then they must have been hiding some place near here, and saw the Moqui
pass in?" suggested Bob, fully aroused by now.

"That seems to be what happened," Frank observed. "But here comes
Charley Moi with the guns. See how he dodges about, so as to keep hidden
from the view of anybody up in those windows above, which we can't
glimpse from here."

When Bob eagerly took his repeating rifle from the hands of the Chinaman
he exhibited all the evidence of great satisfaction; for he heaved a
sigh of relief, and fondled his weapon in a way that caused his comrade
to smile.

"I feel better now," Bob confessed; "because, to tell the honest truth,
when you broke the news so suddenly it nearly gave me heart failure,
Frank, to think that if those rascals sprang out