We plodded on for about an hour, then stopped simultaneously.  At first I thought that the horror of the situation had affected my brain, but the fact that Holman had stopped abruptly at the same moment as I did choked back the cold fear that had rushed upon me.  I was not insane!  Holman was listening too!  I seemed to feel that the tiny thread of sound which had set my pulses beating madly had also keyed him up to the highest tension.

After a minute of intense silence he put a question.

“Did you hear anything?”

“Did you?” I stammered.

“Are we mad, Verslun?” he asked hoarsely.  “I thought—­” He stopped and moved close to me.  I heard his quick breathing as he groped to find me.

“Verslun, did you hear?” he whispered, gripping my arm.  “I heard her speak.”

“I thought I did,” I breathed.  “Perhaps—­perhaps it was an echo.”

For a few minutes we stood, our ears searching for the sound that had disturbed us.  We seemed afraid to call out—­afraid to quench the little spark of hope which had suddenly flared up in the despair that filled our breasts.  We knew that our ears had lied, and we tried to lengthen the thrill by remaining perfectly silent.

The sound came again, and Holman sent a wild cry into the night that hemmed us in.  We were not insane!  The spark of hope blazed as we rushed headlong forward.  The silvery voice of Barbara Herndon had come to us again through the terrible gloom!

[Illustration]

CHAPTER XXI

TOGETHER AGAIN

It is impossible to set down any statement that will enable the reader to form a mental picture of the meeting which took place in that spot of eternal night.  Hands groped for hands in the darkness, and sobs and cries and words of comfort went out into the silence.  Edith and Barbara Herndon wept, the Professor shrieked out denunciations of Leith, and Holman and I were nearly choked by the lumps that rose in our throats.

Explanations came in broken sentences.  The Professor’s anger prevented him from giving the story in detail, and the girls were not in a condition to give a lucid account of their sufferings since the night we had left them to investigate the light in the hills.  We gathered from the hysterical utterances, however, that Leith had rushed them to the hills on hearing from the escaped dancer that we had dodged the fate he intended for us when he had dispatched us to the table of the centipede.  The reduction in his bodyguard caused him to make immediately for the secret retreat, and as he considered it inadvisable to press his argument with the Professor and Edith at that moment, he had lowered his three prisoners into the devil chamber into which we had accidentally fallen.

“This is the place you mentioned to me the night you left the camp,” said the Professor.

“We mentioned?” repeated Holman in amazement.  “We didn’t know the place existed till we rolled into it!”