what the trouble was.

The shielding had been removed from the atomic motors.

He just hung there in the air, not moving. His lean, dark face remained
expressionless, but tears welled up in his eyes and spilled over,
spreading their dampness over his lids.

The motors would run, all right. The ship could take him to Earth. But
the radiation leakage from those motors would kill him long before he
made it home. It would take ten days to make it back to base, and
twenty-four hours of exposure to the deadly radiation from those engines
would be enough to insure his death from radiation sickness.

His eyes were blurring from the film of tears that covered them; without
gravity to move the liquid, it just pooled there, distorting his vision.
He blinked the tears away, then wiped his face with his free hand.

Now what?

He was the only man left alive on the _Shane_, and none of the lifeboats
had escaped. The Rat cruisers had seen to that.

* * * * *

They weren't really rats, those people. Not literally. They looked
humanoid enough to enable plastic surgeons to disguise a human being as
one of them, although it meant sacrificing the little fingers and little
toes to imitate the four-digited Rats. The Rats were at a disadvantage
there; they couldn't add any fingers. But the Rats had other
advantages--they bred and fought like, well, like rats.

Not that human beings couldn't equal them or even surpass them in
ferocity, if necessary. But the Rats had nearly a thousand years of
progress over Earth. Their Industrial Revolution had occurred while the
Angles and the Saxons and the Jutes were pushing the Britons into Wales.
They had put their first artificial satellites into orbit while King
Alfred the Great was fighting off the Danes.

They hadn't developed as rapidly as Man had. It took them roughly twice
as long to go from one step to the next, so that their actual
superiority was only a matter of five hundred years, and Man was
catching up rapidly. Unfortunately, Man hadn't caught up yet.

The first meeting of the two races had taken place in interstellar
space, and had seemed friendly enough. Two ships had come within
detector distance of each other, and had circled warily. It was almost a
perfect example of the Leinster Hypothesis; neither knew where the
other's home world was located, and neither could go back home for fear
that the other would be able to follow. But the Leinster Hyp