first protect the brains, his most cherished possession?"

Eliot Leithgow knew what this meant. The Hawk had promised the brains
in that machine--brains of five renowned scientists, kept cruelly,
unnaturally alive by Dr. Ku--that he would destroy them. And his
promises were always kept.

There was no evading the logic of this reasoning. The Master Scientist
nodded. "Yes," he answered. "He certainly would."

"I couldn't damage the case they were in," Carse continued. "The whole
device seemed self-contained. It means just one thing: special
protection. Since the mechanism for invisibility survived the crashing
of the dome, we may be sure that the brain machine did too. And more
than that: we may assume that there was special protection for the
most precious thing of all to Dr. Ku Sui--his own life."

Friday's mouth gaped open. The old scientist cried out:

"My God! Ku Sui--still alive?"

"It would seem so," said Hawk Carse.

He amplified his evidence. "Look at these space-suits we're wearing.
We got them and escaped by them, but they're Dr. Ku's. Couldn't he
have protected himself with one too? He had plenty of time. And then
the construction of the asteroid's buildings--all metal, with tight,
sealed doors! Oh, stupid, stupid! Why didn't I see it all before?
Here, in my weakness and sickness, I thought we'd killed Ku Sui and
destroyed the coordinated brains!"

Leithgow looked suddenly very old and tired. The calamity did not end
there. There were other angles, and an immediate one of high danger.
In a lifeless voice he said:

"Carse, our whole situation's changed by this. We intended to go
straight to my laboratory, but we may not be able to. The laboratory
may already be closed to us. And even if not, there'd be a big risk in
going there."

"Closed to us by what?" the Hawk demanded sharply. "At risk from
what?"

Old Leithgow pressed his hands over his face. "Let me think a moment,"
he said.

* * * * *

There were very good reasons why Eliot Leithgow maintained his chief
laboratory on the dangerous Satellite III. Other planets might have
offered more friendly locations, but III possessed stores of
accessible minerals valuable to the scientist's varied work, and its
position in the solar system was most convenient, being roughly
halfway between Earth and the outermost frontiers. Leithgow had
counterbalanced the inherent peril of the laboratory's location by
ingenious camoufl