* * * *

Reluctantly, Marin retracted the instruments into the digger. He
turned it around and, with not too much regard for the terrain, let it
roar. The treads tossed dirt high in the air. Animals fled squealing
from in front of him. If the grove was small enough, he went around
it, otherwise he went through and left matchsticks behind.

He skidded the crawler ponderously to halt near the edge of the
settlement. The center of activity was the warehouse. Pickups wheeled
in and out, transferring supplies to a cleared area outside. He found
Hafner in a corner of the warehouse, talking to the engineer.

Hafner turned around when he came up. "Your mice have grown, Marin."

Marin looked down. The robot cat lay on the floor. He knelt and
examined it. The steel skeleton hadn't broken; it had been bent,
badly. The tough plastic skin had been torn off and, inside, the
delicate mechanism had been chewed into an unrecognizable mass.

Around the cat were rats, twenty or thirty of them, huge by any
standards. The cat had fought; the dead animals were headless or
disemboweled, unbelievably battered. But the robot had been
outnumbered.

Biological Survey had said there weren't any rats on Glade. They had
also said that about mice. What was the key to their error?

[Illustration]

The biologist stood up. "What are you going to do about it?"

"Build another warehouse, two-foot-thick fused dirt floors, monolithic
construction. Transfer all perishables to it."

Marin nodded. That would do it. It would take time, of course, and
power, all they could draw out of the recently set up atomic
generator. All other construction would have to be suspended. No
wonder Hafner was disturbed.

"Why not build more cats?" Marin suggested.

The executive smiled nastily. "You weren't here when we opened the
doors. The warehouse was swarming with rats. How many robot cats would
we need--five, fifteen? I don't know. Anyway the engineer tells me we
have enough parts to build three more cats. The one lying there can't
be salvaged."

It didn't take an engineer to see that, thought Marin.

Hafner continued, "If we need more, we'll have to rob the computer in
the spaceship. I refuse to permit that."

Obviously he would. The spaceship was the only link with Earth until
the next expedition brought more colonists. No exec in his right mind
would permit the ship to be crippled.

But why had Hafner called him back? Merely to