aranoff had done
this."

"But you're dead!" protested the detective. "We killed you when we
destroyed your helicopter."

"You killed merely an assistant who had disobeyed my orders. Had I not
decreed his death, he would be alive to-day. I could kill you as you
stand there; you into nothingness; but I do not choose to do so--yet.
Other attempts I have made you have frustrated, but this time I shall
succeed. I will institute a reign of terror which will bring your
rich, foolish country to its knees. Listen, while I give you a taste
of my power. The city of Charleston is about to be destroyed."

A thunderous roaring filled the air. Crash followed crash in rapid
succession. It sounded as though all the noise of the universe had
been concentrated in the cavern. The earth shook and rocked like a
restless sea. From above came cries of terror.

The three men in the cavern were thrown to the ground. Shaken by the
fall and deafened by the tumult, they hung onto irregularities of the
rock on which they lay. Gradually the tumult and the shaking subsided.
The cries from above became more apparent. Silence finally reigned in
the cavern and the metallic Voice spoke again.

"Go back now and look at Charleston and you will see what to expect.
The rest of your cities will soon share the same fate. Beware of
trying to trace my movements, for your lives are in the hollow of my
hand."

* * * * *

The voice died away in silence. From the edge of the hole came a cry.
A Fort Moultrie officer was peering down at them.

"Are you all right down there?" he hailed.

"Right as hops," called Dr. Bird cheerfully. "What happened up above?"

"I don't know, Doctor. There seems to be a lot of smoke and fire over
in the direction of the city. I expect the quake shook them up a
little this time. What shall we do now?"

"We're ready to come up. First I'm going to send up a wheelbarrow full
of yellow powder. Rig a crane to lift it, for it's too heavy to try to
hoist with ropes."

With the aid of Carnes and Dr. Lassen, Dr. Bird collected a few cubic
inches of the yellow powder from the ridges in the rock. He made the
wheelbarrow containing it fast to the wire cables of the crane and
gave the signal. Slowly it was raised to the surface. When it had
safely reached there he turned to his companions.

"Grab a rope and let's go," he said.

In a few moments they were on the upper level. With the efforts of
half a doz