as they captured us. And eventually someone will happen
along who'll weaken under torture. Then--"

* * * * *

He stopped. A dread vision filled his mind of Earth depopulated by the
feebly ferocious Rogans, of rank on rank of Earth's vast armies
falling in stricken rows at the shock of the Rogans' tubes.

Greca caught the vision. She nodded. "Yes, that is what would happen
if they found ways of reaching your globe."

"But, God, Brand, we can't allow that!" cried Dex. "We've got to find
a way to spike the guns of these walking gas-pipes, somehow!"

Brand sighed heavily. "We are two against hundreds of thousands. We
are bare-handed, and the Rogans have those damned tubes. Anyway, we
are on the verge of death at this very moment. What under heaven can
we do to spike their guns?"

He was silent a moment: and in the silence the steady hum from the
domed building outside came to his ears.

"What's in that big, round topped building, Greca?" he asked quietly.

"I do not know, exactly," replied the girl. "There is some sort of
machinery in it, and to it go connecting beams from all the square
metal plates everywhere. That is all I know."

Brand started to question her further, but her time was up. The two
guards poked their loathsome pumpkin heads in the doorway and
contemptuously beckoned her out. She answered resignedly, in the
piping Rogan tongue, and went with them. But she turned to wave shyly,
commiseratingly at the two men; and the expression in her clear blue
eyes as they rested on Brand made his heart contract and then leap on
with a mighty bound.

"We have in ally in her," murmured Brand. "Though God only knows if
that will mean anything to us...."

CHAPTER IV

_In the Tower_

"What I can't figure out," said Dex, striding up and down the big bare
room, "is why we're needed to tell them about the atomic motor.
They've got our ship, and three others besides. I should think they
could learn about the motor just by taking it apart and studying it."

Brand grinned mirthlessly, recalling the three years of intensive
study it had taken him to learn the refinements of atomic motive
power. "If you'd ever qualified as a space navigator, Dex, you'd know
better. The Rogans are an advanced race; their control of polar
magnetism and the marvelously high-powered telescopes Greca mentions
prove that; but I doubt if they could ever analyze that atomic motor
with no hint as to h