“Heave her!”

Up swung the stone, aside.  It slid over the wet rock.  There, in its place, gaped a black hole that penetrated unknown depths.

Steam billowed up—­or rather, vapor distinctly warm to the touch.  And from very far below, much louder boomed the roar of rushing waters.  The Legionaries knew, now, what had caused the dull, roaring sound.  Unmistakably a furious cascade was boiling, swirling away, down there at undetermined distances of blackness.

The boldest men among the little group of fugitives felt the crawl and fingering of a very great dread at their hearts.  Behind them lay the labyrinth, with what pitfalls none could tell and with the Jannati Shahr men perhaps already penetrating into the crypt.  Around them loomed the black, wet walls of this lowest stone dungeon with but one other exit—­the pit at their feet.

The Master threw himself prone on the slippery floor, took one of the lamps and lowered it, by the chain, to its capacity.  Smoke and vapor arose about his head as he peered down.

“Well, what is it?” demanded Bohannan, also squinting down, as he bent over the hole.  “What do you see?”

“Nothing,” the Master answered.  “Nothing definite.”

He could, in fact, be sure of nothing.  But it seemed to him that, very far below, he could make out something like a swift, liquid blackness, streaked with dim-speeding lines of white that dissolved with phantasmagoric rapidity; a racing flood that roared and set the solid rock a-quiver in its mad tumult.

“Faith, an underground river of hot water!” ejaculated the Irishman with an oath.  “Some river!”

“Warm water, at any rate,” the Master judged, getting up again.  A strange smile was in his eyes, by the smoky lamplight.  “Well, men, this is our way out.  The Arabs are not going to have any slaughter of victims, here.  And what is more, they’ll capture no dead bodies of white men, in this trap!  There’ll be at least ten skulls missing from that interesting golden Pyramid of Ayeshah!”

“For God’s sake!” the major stammered.  “What—­what are you going to—­do, now?  Jump down that shaft?”

“Exactly.  Your perspicacity does you credit, Major.”

“Sure, you’ll never catch me jumping!”

“Gentlemen,” the Master said, in a low, quiet voice, “I regret to state that we have one coward among us.”

CHAPTER XLVIII

THE RIVER OF NIGHT

The major’s clenched fist was caught as it drove, by a scientific guard from the Master’s right.  The Master dropped his lamp, and with a straight left-hander sprawled Bohannan on the slimy pave.  Impersonally he stood over the crazed Celt.

“Will you jump, voluntarily,” demanded he, “or shall we be under the painful necessity of having to throw you down that pit?”

Enough rationality remained in the major to spur his pride.  He crawled to his feet, chastened.