a sense of
those unseen presences, of gathering, furtive hosts about them,
waiting--waiting for what?

What was this strange sense of tension, of foreboding, that hung in
the air? Was the professor wrong? Were they being led to their doom,
after all?

He was soon to know, for now the gallery they had been traversing
levelled out into a series of short passages, each barred by a heavy
stone door, and finally they were led into a small, square room,
barely large enough to admit them all.

There, with gestures toward the far end, their guides left them.

The door closed, and almost immediately another on the opposite side
opened, slowly at first, then wider and wider, admitting a rush of
water that promptly filled the room.

Stepping wonderingly out, they found themselves on the upper level,
beside the second of the two smaller pyramids.

* * * * *

"Whew!" gasped Larry, as they stood looking around, still a little
dazed. "These people are sure quick-change artists! First they try to
feed you to their gods, then they save you from almost as bad a fate.
Dizzy, I call it!"

"Quite understandable, I should say," declared the professor. "Unable
to cope with Von Ullrich themselves, they think perhaps we may be able
to."

"Well, let's hope they're right!" grimly. "If once I get my hands on
him--"

He broke off suddenly, as Captain Petersen called out:

"The _Nereid_! There she is!"

Following with their eyes the bright segment cut into the murky depths
by his flashlight, they saw the familiar outlines of their craft; and
close beside her lay the U-boat.

A feverish activity seemed to be going on between the two submarines.

"They're changing cargo!" cried Larry. "Quick! We've got them now!"

But the progress they were able to make, hampered by their heavy
suits, was maddeningly slow. Their searchlights, moreover, betrayed
their approach. Before they could reach the scene, most of the sailors
had abandoned their task and piled into the U-boat.

Arms swinging wildly, Von Ullrich stood beside it, trying to rally
then. Refusing to risk combat, however, since they were unable to use
their deadly hand-grenades under water, they continued clambering up
the sides of their submersible and shoving down through its
conning-tower hatch.

Now a figure in a familiar pressure-suit broke away and started toward
the advancing party.

It was Diane!

* * * *