"Maybe one of the sounds that the glacier makes," he proffered.
"It is possible. But—"
"Well?"
"It seemed to come right out of the rocks; but that isn't possible."
"We'll see about that, Bill."
He pressed a button, and the strong rays of his electric light played upon the dark rock and the blue ice. The light in his left hand, he dropped to his knees and looked under. I heard an exclamation and saw him move forward. At that instant a sound brought me up and whirled me around.
My heart was in my throat. I could have sworn that the sound had issued from some point just behind me. But there was nothing to be seen there—only the walls of blue ice and the blue sky above.
"Must have been some sound made by the glacier slipping or something," I told myself.
I turned—to find that Milton Rhodes had vanished!
For a little space I stood staring and wondering, then called in a low voice: