certainty how it is
communicated."

"What are you doing?" asked Phillips.

"Isolation. It is all we _can_ do, until our medical men can make some
progress. We evacuated an asteroid colony and began to ship into it any
person showing any of the symptoms, using a cruiser piloted by remote
control. That was where we slipped."

"How?"

"On the last trip--unless we have not really collected _all_ the
sufferers--we lost control. Someone being transported knew his
spaceships. Shortly thereafter, a gibbering lunatic got on the screen
and threatened the escorting rocket. He announced the cruiser would head
for Mars, where the passengers would demand their freedom. They are past
reasoning with."

"Can't say I really blame them," Phillips remarked.

"Blame them? Of course not! Neither do I. What has that to do with it?
What has the Council so worried is that this thing will get loose on
Mars, that it may even be carried to Earth and Venus. There are over a
hundred persons in that ship, no longer responsible for their actions
but capable of causing deaths by the billions. We _want_ to help them,
but we simply must hold the line on this quarantine until we solve the
medical problem."

* * * * *

They stared at him in silence, and Phillips noticed that the old man's
forehead was moist with tiny beads of perspiration.

"Don't you see? They are as good as dead. No knowledge or help of man
can save them--as of this moment. If we are _ever_ to be of any help, we
must prevent a worse catastrophe.

"Yes, the survival ship is a world in itself, but this world must die!"

For a minute or two, it seemed to Phillips that he could hear each
person in the control room breathing. Finally, there was a small sound
of cloth rubbing on metal as Brecken stirred. "Why pick on us?" he
rasped from his seat on the deck. "I'm no volunteer!"

"I know what you are," replied Varret sharply. "I know what you all are.
You have been chosen for this mission of murder, because you are the
only people in our culture who are capable of this kind of violence. You
have broken our laws, and this is your punishment.

"It would take us too long to find others like you who had merely never
faced the same circumstances that sent you four to Luna. We have made
attempts to attack this vessel. Manned by normal men, our ships could
accomplish nothing."

"Why not?" asked Phillips.

"_The crews found they could not kill!_"

"