's glory enough for all," laughed Joe. "We'll have to tell Doctor
Dale and Frank Brandon about this. We've got so many tips from them that
it's about time we made it the other way around."

They were so excited about this new development which they had stumbled
upon purely through accident that they sat talking about it for a long
time until Bob chanced to look at his watch.

"Just have time for the last selection," he remarked, as he reconnected
the aerial. "We'll wind up in the regular way this time. It's an aria
from Lucia and I don't want to miss it."

He had some difficulty in making his adjustment, as there was a lot of
interference at the moment.

"Raft of amateurs horning in," he muttered. "All of them seem to have
chosen just this time to do it. I wonder----"

He stopped as though he had been shot, and listened intently. Then he
beckoned to the others to adjust their headphones.

Into the receiver was coming a succession of stuttering sounds that
eventually succeeded in framing intelligible words. Ordinarily this
might have provoked laughter, but not now. They had heard that voice
before.

It was the voice of Dan Cassey!

CHAPTER IV

A PUZZLING MYSTERY

For the second time that evening the radio boys thought they must be
dreaming.

Cassey! Cassey the swindler, whom they had compelled to make restitution
to the victim he had wronged. Cassey the thug, whom they had captured in
that wild chase after he had looted the safe and nearly killed the
operator in the sending station. Cassey the convict, who, to their
certain knowledge, had been sentenced to a long term in prison.

What was Cassey doing over the radio? That it was that scoundrel they
had no doubt. The stuttering, the tones of the voice, the occasional
whistle which he indulged in in order to go on--all these things they
recognized perfectly. It was the wildest kind of improbability that he
had a double anywhere who could reproduce him so perfectly.

Gone now was any thought of the aria from Lucia. Bob motioned
frantically to Jimmy to hand him a pencil and a sheet of paper. Then he
jotted down the words, as after great efforts they fell one by one from
the stutterer's lips. As Bob did this he bent over the paper in frowning
perplexity. The words themselves were intelligible, but they did not
seem to make sense, nor was there anywhere a connected sentence.

Finally the stammering voice ceased, and after they had waited several
minut