"That's what I've been asking myself. I've thought it over and I believe I've found the answer. Either he was radioing to the Calomares ranch in Old Mexico where father probably is held a prisoner, or else he was sending a message to the fellows who stole our airplane."
Bob, the belligerent growled in his throat.
"The big stiff," he muttered. "I'll go get him now and we'll choke it out of him."
He half rose from his chair, but his father pushed him back.
"Don't blame you, Bob," said Jack, grinning. "It's what I wanted to do myself. But I believe there is more to be gained by watching Rollins—at least until we have more to go on."
"Probably," said Frank, "if we put it up to him now, he'd be able to lie out of it."
"But he couldn't lie out of being seen with Remedios," said Bob. "Or of using the radio."
"Frank is right, though," declared Jack. "Rollins would frame some alibi, and all we'd succeed in doing would be to put him on his guard."
Mr. Temple had been thinking deeply. Now he interrupted.
"Jack is probably correct in his surmise as to who Rollins was calling by radio," he said. "Probably this Calomares ranch is headquarters for the Mexican rebels who are making trouble for us. If it was the ranch that Rollins called, he may have been making his report on today's proceedings. But if he was calling the airplane, that is a more serious matter. It may mean trouble for us tonight, perhaps another attack."