12;we'd sure get broken in on."

Joe Marion, who had been taken on as an understudy by Curlie, was at the present time working without pay. At times when trouble developed on two different wave lengths at once, he took a hand and helped out. For the most part he merely looked, listened and learned.

His pal he held in the greatest admiration. And who would not? Had he not, when this great big new thing, the radiophone, came leaping right into the world from nowhere, been able to take a hand from the very beginning and become at once a valuable servant of his beloved country? Had he not at times detected meddlers who were endangering the lives of men upon the high seas? Had he not at one time received the highest of commendations from the great chief of this secret service of the air?

To Joe there was something weirdly fascinating about the whole business. Here they were, two boys in the tower of the highest building in a great city. Five people knew of their presence. These five were high up in the radio secret service. No message sent out by them could ever be traced back to its source. They did not use the air. That would be dangerous, easily traced. They did not use the telephone alone. That, too, would be dangerous. But when a radiophone had been connected to the telephone wire and tuned to a certain wave length, then they talked and not even the person they talked with would ever know whence came the message. This was a necessary precaution for, from this very tower, dangerous bands of criminals, gangs of smugglers, and all other types of law-breakers would ultimately be brought to justice. And if these but knew of the presence of this boy in his tower room, some dark night that tower would be rocked by an exploding bomb and the boy in his room would be shaken to earth like a young mud-wasp in his nest.

"I'll tell you," said Curlie, as he rose to answer a tap on the door, "I believe that affair last night was some big thing; but what it was I can't even guess."

He opened the door to let in Coles Masters, his relief, then motioning to Joe he took his cap and left the room. Down the winding stairs which led to the elevator several stories lower down they made their way in silence, at last to enter a cage and be silently dropped to the ground hundreds of feet below.

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