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 Hampton ranch again?”

Jack interrupted excitedly.

“No, Frank, don’t you see!” he said.  “Bob is thinking of the radio here in the cave.  Aren’t you, Bob?  I’m a simpleton not to have thought of it before.”

“Well,” said Bob, “we’ve all been so excited, that’s not to be wondered at.  But while I mounted guard here during your breakfast, I had a chance to calm down and do some thinking.”