oceed," said the
leader.

* * * * *

He pointed toward one of the gargantuan work benches, and two of the
Rogans slid down from it a contrivance that looked familiar to Dex. An
instant's scrutiny showed him why it was familiar: it was a partly
dismantled atomic motor.

In spite of the ordeal that faced him, Dex felt a thrill of elation
as he looked at the motor. In its scattered state, it told a mute
story: a story of long and intensive study by the Rogans, which had
yielded them no results! Only too obviously, the intricate secret of
atomic power had not let itself be solved.

On the heels of the elation that filled his heart, came a sickening
realization of his dilemma. He could not have told the Rogans what
they wanted to know even if he had wished to! He himself didn't know
the principles of the atomic engine. As Brand had remarked, he was no
space navigator; he was simply a prosaic lieutenant, competent only at
fighting, not at all versed in science.

He knew, though, that it would do no good to assert his ignorance to
the Rogans. They simply wouldn't believe him.

"You will rebuild this engine for us," ordered the tall leader,
"showing us the purpose of each part, and how the power is extracted
from the fuel. After that you will set it running for us, and instruct
us in its control."

Dex braced himself. His final moment had come.

By way of indicating his refusal he looked away from the dismantled
motor and said nothing. The Rogan repeated his command. Dex made no
move. Then the leader acted.

He said something to the Rogan guards who had been standing by all
this while, alert against an outbreak from their prisoner. Dex was
caught up, carried to one of the metal racks, and thrown down on its
calibrated bed. Loops of metal, like handcuffs, were snapped around
his wrists and ankles; and a metal hoop was clamped over his throat,
pinning him to the torture rack. Resistance would have been useless,
and Dex submitted quietly.

* * * * *

The contrivance, with him on it, was wheeled toward the barred door.
It was halted at a spot marked on the floor, about thirty feet from
the bars. The Rogan leader stepped alongside the rack, with Greca
trembling beside him.

Dex closed his eyes for a moment, grimly marshaling strength of will
to go through the trial that was just beginning.

The Rogan leader depressed another lever in the rock wall. The b