It
was square, with a dimension of about five feet on the edge.

"It's a trap-door, all right," he announced. "And we--are going to
open it!"

"One would need a rope or a long lever to do that, my Captain," put
in Leclair. "It is obvious that a man, or men, standing on the trap,
could not raise it. And it is too large to straddle."

The Master arose, stripped off his tunic and passed it through
the ring. He twisted the tunic and gave one end to the lieutenant.
Himself, he took the other.

"Get hold, everybody!" he commanded. "And be sure you're not standing
on the trap!"

All laid hold on the ends of the coat. With a "One, two,
three!" from the Master, the Legionaries threw all their muscle into
the lift. "Now, men! Heave her once more!"

The stone gave. The Legionaries doubled their efforts, with panting
breath, feet that slipped on the dank floor, grunts of labor.

"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 oa