down their
silence than were his questions.

Bob remained at the doorway to avoid the risk of recognition by
Morales and Von Arnheim as the youth who had foiled their attempt to
steal Mr. Hampton's papers from his Long Island home. Jack, who had no
means of knowing how much the traitor, Rollins, might have told Von
Arnheim in the past about Mr. Hampton's personal affairs, watched
keenly for some indication on the German's part that he had formed an
idea as to their identity, but none was forthcoming.

Jack was correspondingly elated.

"I suppose," he said to Frank, after Morales and Von Arnheim had been
fed and returned to the other side of the cave, "that Rollins never
bothered to speak about us because we were just boys. Then, too, you
fellows arrived only the very day that we discovered Rollins's
treachery and put a stop to his communications with these people."

"That may all be true," said Frank. "Probably it is. Just the same,
Von Arnheim and Morales are bound to put two and two together and make
a shrewd guess as to our identities, even if they say nothing to us
about the matter.

"But," he added, confidently, "what if they do? We have them prisoners
now and if we keep them well guarded until we have rescued your
father, what does it matter how much they know?"

Jack nodded agreement.

"We'll have to keep mighty strict watch, though," he said. "Well, now
let's feed this American, Stone. I'll draw straws with you to see who
keeps guard while Bob comes to get his breakfast at the same time. He
wants to talk to Stone, he said."

CHAPTER XX

CONFERRING BY RADIO

Bob, however, told his companions he had decided not to interview
Stone for the time being, and explained his reason, as well as what he
hoped to gain from conversation with the prisoner.

"I believe," he declared, "that Stone is a warm-hearted, adventurous
young fellow with no particular love for the Mexican rebels, but
merely serving under their banner for the excitement. And I believe if
we approach him right we can win his help in rescuing Mr. Hampton. He
must know a good deal about this Calomares ranch and if we can get him
to give us some pointers it will be worth while.

"That was what I had in mind last night. But mounting guard here this
morning I had time to think it over, and I decided we had better go
slow and, if possible, get the advice of my father on the matter."

"But how could you do that?" asked Frank. "Go back to