With shouts of consternation from Felipe ringing in our ears, we leaped after her.

“Desiree!” cried Harry.  “Come back, Desiree!”

There was no answer, but echoing back from the night before us came faint reverberations—­could they be footsteps!  What folly!  For I had thought that she had merely intended to frighten poor Felipe, and now—­

“Desiree!” Harry called again with all the strength of his lungs.  “Desiree!”

Again there was no answer.  Then we entered the cave together.  I remember that as we passed within I turned and saw Felipe staring with white face and eyes filled with terror.

A hundred feet and we were encompassed by the most intense darkness.  I muttered:  “This is folly; let us get a light,” and tried to hold Harry back.  But he pushed me aside and groped on, crying:  “Desiree!  Come back, Desiree!”

What could I do?  I followed.

Suddenly a scream resounded through the cavern.  Multiplied and echoed by the black walls, it was inhuman, shot with terror, profoundly horrible.

A tremor ran through me from head to foot; beside me I heard Harry gasp with a nameless fear.  An instant later we dashed forward into the darkness.

How long we ran I could never tell; probably a few seconds, possibly as many minutes.

On we rushed, blindly, impelled not by reason, but by the memory of that terrible cry, side by side, gasping, fearful.  And then—­

A step into thin air—­a mighty effort to recover a footing—­a wild instant of despair and pawing helpless agony.  Then blackness and oblivion.

Chapter VI.

Captured.

The fall—­was it ten feet or a thousand?  I shall never know.  Hurtling headlong through space, a man can scarcely be expected to keep his wits about him.

Actually, my only impression was of righteous indignation; my memory is that I cursed aloud, but Harry denies it.

But it could not have been for long, for when we struck the water at the bottom we were but slightly stunned by the impact.  To this Harry has since agreed; he must have been as lucky as myself, for I took it headlong with a clean cleavage.

I rose to the top, sputtering, and flung out my arms in the attempt to swim—­or, rather, to keep afloat—­and was overjoyed to find my arms and legs answer to the call of the brain.

About me was blackest night and utter silence, save a low, unbroken murmur, unlike any other sound, hardly to be heard.  It was in my effort to account for it that I first became aware of the fact that the water was a stream, and a moving one—­moving with incredible swiftness, smooth and all but silent.  As soon as I became convinced of this I gave up all attempt to swim, and satisfied myself with keeping my head above the surface and drifting with the current.

Then I thought of Harry, and called his name aloud many times.  The reverberations throughout the cave were as the report of a thousand cannon; but there was no response.