"There it is again!" said Rhodes.
I flashed on my electric light, to the full power.
"A whisper!" I exclaimed. "Angel, demon, human or what? And, great Heaven, Milton!"
"What now, Bill?" he asked quickly.
"It's something behind us!"
He started. He turned his light up the tunnel, and for some moments we stood peering intently. Not a moving thing was to be seen there, however—only the moving shadows.
"Again!" said Milton Rhodes. "But it isn't a whisper, Bill. And it didn't come from up there."
"The thing," I told him, "could be hiding in shadow—hiding and watching us."
"It's not up there; it's ahead."
"Wherever it is, what on earth can it be? Whatever it is, what does this mean?"