usness. He opened his eyes, blinking in broad daylight.
He stared about him, and the first thing he saw was Luke Evans,
regarding him anxiously from a little distance away. He saw that it
was Luke who had spoken.

He had heard the old man distinctly. The condition of inaudibility was
gone.

Not that of invisibility. Dick stared about him in bewilderment. For a
moment, before he quite realized what had happened to him, he thought
he had lost his mind. Underneath him was a thick rug, beneath his head
a pillow; he could feel both of them, and yet all he could see was the
open country, a clearing with shrubbery on either side, and, beyond
that, a luxurious growth of tropical trees. Under him, to all visual
appearance, was the bare ground.

He moved, and heard the clank of chains. He looked down at himself.
His wrists were loosely linked to a chain that seemed to stretch tight
into vacancy and end in nothing. His ankles were bound likewise.

And both chains appeared to be of solid silver, but thick enough to
give them the strength of iron!

Then he perceived that old Evans was bound in the same way.

"Rennell! Rennell!" repeated the old man in a sort of whimper. "Thank
God you've come out of it! I was afraid you were dead."

"What's happened?" asked Dick. "Where are we? Didn't they get us?"

"They've got us, damn them!" snarled old Evans. "All the rest burned
to cinders, those fine fellows, Rennell! You were thrown unconscious,
but none of my tough old bones were hurt. They pulled us out of the
wreckage and brought us in here and tied us with these silver chains."

"In here? But where are we?" demanded Dick, trying to pass his hand
across his aching forehead, and realizing that the chain, though it
seemed fastened to nothing, was perfectly taut.

* * * * *

"In one of their damned invisible houses," whimpered the old man.
"They're fireproof. Nearly all our bombs fell on the tarmac, and they
did hardly any damage at all. One of those devils was bragging about
it to me. I couldn't see anything but his eyes. And they've taken away
my gas-box," wailed old Luke.

Dick cursed comprehensively and was silent. The burning rage that
filled him left him incapable of other utterance. Silver chains! They
must be madmen--yes, that was the only explanation. Madmen who had
escaped from somewhere, obtained possession of scientific secrets, and
banded themselves together to overcome the world. If h