“Radio is all I can think of,” he told himself. “Lots of sense to that. We had a portable outfit complete in a box and decided not to bring it.”

He was to know the answer to all this in due time. For the present it was to remain the freshest mystery of the grim old Citadel.

Presently Curlie dropped back to his place beside the fire, which by this time had burned itself down to a dark red bed of blackening coals.

“It’s all done by the aid of batteries,” he mumbled as if speaking to himself. “Did that visitor of mine come round and try to break your head?” he asked, once more staring at Johnny’s bandages.

“No, well,—perhaps, who can tell? It was some native or other.”

Settling back in his place Johnny told of the night’s encounter. “That proves,” he ended, “that some places are not as safe as they seem.”

“And that you may expect a doctor to appear upon the scene at any time,” laughed Curlie.

“Anyway,” said Johnny quite soberly, “he was a handy person to meet. Only hope I get an opportunity to repay him.”

Once more silence, the great, ominous, silence of the Citadel hung over all. For a full ten minutes no one spoke. It was old Pompee who at last broke the silence.

“Once,” his deep voice rumbled, “men lay upon the ground as we rest here now, waiting for sleep to come. There were hundreds, perhaps thousands of them, prisoners condemned to toil upon the unfinished walls.