It was faint, so faint that it seemed to whisper to them through miles and miles of space--yet they knew that it was a voice! "Some one is shouting," spoke Aldous tensely.

"Joanne, my darling, stand around the face of the wall so flying rock will not strike you and I will answer with my pistol!" When he had placed her in safety from split lead and rock chips, he drew his automatic and fired it close up against the choked tunnel.

He fired five times, steadily, counting three between each shot, and then he placed his ear to the mass of stone and earth and listened.

Joanne slipped to him like a shadow.

Her hand sought his, and they held their breaths.