. If there's anybody on this island we don't know
about, it ought to be our first business to find out. I think I'll
take a peep into this mysterious cave."

He made a step forward, but Ruth's hand tightened on his arm and he
stopped.

"Do you think you'd better risk it, Allen?" she asked. "How do you
know what may be in there. Suppose--suppose----"

"Suppose what?" he asked with a whimsical smile.

"Suppose anything should happen to you?" she half whispered.

"Nothing will happen to me," he rejoined. "Not that it matters much
anyway," he added bitterly, as the thought swept over him of the black
cloud of suspicion that hung above him.

"Just give me a minute, Ruth," he pleaded, hating himself for his
reckless words as he saw the pained look in her eyes. "I won't go in
for more than twenty or thirty feet, just to see if there's anything
about this place that we really ought to know. You stay here and I'll
be back before you fairly know I've gone."

She reluctantly loosened her grasp of his arm and he plunged forward
into the darkness.

For the first ten feet or so, the going was rendered rather difficult
by projecting bits of rock that caught at his clothes and impeded his
progress. But then the passage widened out steadily until he could not
feel the sides even when his arms were stretched to their utmost limit.

The light that had followed him from the small entrance finally
vanished, and he went forward with the utmost caution, carefully
planting each foot for the next step. At any moment, for all he knew,
he might find himself on the brink of a precipice.

"Black as Egypt in here," he muttered to himself, as he felt for the
matches he carried in an oilskin bag in the pocket of his coat. "I
guess I'd better strike a----"

But he never finished the sentence.

A deafening roar resounded through the cavern and he was thrown
violently forward on his hands and knees. Again came that dizzy,
sickening shaking of the earth, that nauseating sense of being lifted
to a height and suddenly let fall, that squirming of the ground beneath
him as though it were a gigantic reptile.

His earlier experience in the open air had been bad enough, but there
at least he had had the sense of space and sunlight and companionship.
Here in the darkness and confinement the horrors of the earthquake were
multiplied.

For more than a minute, which seemed to him an hour, the convulsions of
the earth continued. Then the