ey are walls raised on
those original foundations by the frantic populace, when the
submergence first began, in a vain effort to hold back the tides that
engulfed them."

"And do you think they are of gold?"

"Frankly, no; though I have no doubt you will find plenty of that
element down there."

Nor was the prediction wrong, for modern eyes had never seen such a
treasure house as they beheld when presently the _Nereid_ came to rest
outside that ancient four-walled city and they forced their way
inside.

* * * * *

Though the walls were not of gold, the inner gates were, and the
temples were fairly bursting with the precious metal, as well as rare
jewels, the eyes of a thousand idols gleaming with rubies and
emeralds.

But where was the populace, amid all this prodigious wealth? Was there
no life down here?

Von Ullrich declared through the vibrator of his pressure-suit that he
had heard there was. And as though in substantiation, many of the
temples showed the same bell-jar construction as the pyramids above,
though even stouter, revealing evidences of having been occupied very
recently; but all were flooded and empty. The city was as a city of
the dead.

This ominous sign did not deter the "emperor," however. Ruthlessly he
and his men looted those flooded temples, forcing Professor Stevens
and his party to lend aid in the orgy of pillage.

And all the time, Larry had an uneasy feeling of gathering furtive
hosts about them, waiting--waiting for what?

He confided his fears to no one, though he noted with relief that Von
Ullrich seemed to sense these unseen presences too, for he proceeded
with caution and always kept a strong guard outside.

* * * * *

By early afternoon, the _Nereid_ was one great coffer-chest.

But still the rapacious U-boat commander was unsatisfied, though
Professor Stevens began to have doubts if his craft could lift that
massive weight of plunder to the top of the plateau.

"One more load and we go," he soothed. "A few more pretties for the
little lady!"

Larry writhed, and should have suspected then and there--but as it
was, the blow fell unexpected, stunning.

Filing from the lock, they failed to notice that Von Ullrich and his
crew hung back, until there came a sudden, guttural command, whereupon
Diane was seized and the massive door flung shut in their faces.

Appalled by this overwhelming disaster, the party