at us we would be next
door to helpless. Now let 'em be careful how they play their little
game. But what does it all mean, do you suppose, Frank?"

"I can only make a guess, and that may be wide of the truth," the other
admitted. "By some accident they managed to get on the track of the
Moqui. Though Havasupai thought himself smart, he was no match for such
a cunning rascal as Spanish Joe, who is said to be the best trailer
along the Arizona border. And they followed him right here."

"That was last evening, just when you and I stood there down by the
river, looking through the glasses up at the windows of the rock houses
above," remarked Bob.

"Yes. Perhaps they didn't go up right then." Frank went on. "I admit
that I can't just make out how long ago these tracks were made. A better
trailer might, you see, Bob. If Old Hank Coombs were only here now I'd
be glad to turn the whole business over to him, and play second fiddle."

"But some time between dark and morning these three rascals went in
here, and surprised the hermit of Echo Cave--is that it, Frank?"

"It covers the case all right," came the reply.

"Say, do you think they are up there yet?" asked the Kentucky lad, in an
anxious tone.

"I think they must be, Bob, because all the tracks point one way,
showing that the three men never came back. If they left the cave it
must have been by some other way."

"No use asking why they would want to get in touch with Uncle Felix!"
continued Bob, as if bent on finding out everything he could in
connection with the case.

"We know what their reason was," Frank made answer. "When Abajo, hanging
about the window of our ranch house, heard what we had to say about the
message that came floating down the Colorado in that bottle, and carried
the wonderful news to his employer, Eugene Warringford, he set the game
going that must end right here. He has come with the intention of making
Professor Oswald turn over that option to him; and he'll do it unless
something we can offer prevents."

"But Frank, if the Moqui carried that note of yours to Uncle Felix, he
would be on his guard, and absolutely refuse to sign away the papers?"

"I hope he will, but I fear that those three scamps are up there right
now, trying to coax or bulldoze him into signing," Frank said, with a
tightening of his lips, and a flash of his clear eyes.

"Then we go up, and put a spoke in their wheel, do we?" asked Bob,
looking as if he were ready t