et
in a small oven which he raised to 50 degrees centigrade.

"When this cools, the set will be stable," Mr. Swift said. "But if you
should move any part of it after it cools, all of the organic parts,
like the circuit boards, the insulation, the carbon resistors, etc.,
will oxidize and disappear as gas. You will not even be able to tamper
with a single unit."

"Wonderful, Dad," Tom murmured when the device was finished. "I wish I
had your know-how in microchemistry."

"And I wish I had yours in electronics!" the elder scientist declared
with a chuckle.

After Mr. Swift had installed the device in Exman's star head, Tom used
the electronic brain to inform the robot about the whole scheme.

Both Tom Jr. and Tom Sr. were delighted when Exman showed real
enthusiasm. It replied via the printed tape on the decoder:

DO NOT WORRY, MY FRIENDS. I WILL NOT RESPOND TO ANY ATTEMPTS BY
BRUNGARIAN SCIENTISTS TO COMMUNICATE WITH ME. MY PLANET IS WELL
AWARE OF THEIR DANGEROUS AIMS. HAVING CONQUERED YOUR WORLD, THEY
WOULD NEXT INVADE SPACE.

"Looks as though Exman's got their number, all right!" Tom said with
satisfaction.

Early the next morning Mr. Swift drove Tom to the Enterprises airfield
to meet his friends. Hank Sterling, Bud, and Chow were already on hand,
and Arv Hanson arrived a few moments later. Tom and Bud left the others
to bring Exman in a small panel truck.

Soon the space robot was safely loaded aboard a transport helicopter.
The others took their places inside the cabin.

"Good luck, son!" Mr. Swift forced a smile as he gave Tom a parting
handshake.

"Don't worry, Dad. I'll be back soon!" Tom assured him. The nature of
the trip had been described only vaguely to Mrs. Swift and Sandy in
order to keep them from worrying.

The short hop overwater to Fearing Island was soon completed. Lying just
off the Atlantic coast, Fearing had once been a barren, thumb-shaped
expanse of scrubgrass and sand dunes. Now it was the Swifts' top-secret
rocket base, tightly guarded by drone planes and radar.

As the helicopter approached its destination, Tom radioed for clearance,
then whirred down toward the landing field. The barracks, workshops, and
launching area of the base lay spread out in full view. Cargo rockets
bristled on their launching pads, along with Tom's spaceships, including
the mighty _Titan_, and the oddly shaped _Challenger_ and _Cosmic
Sailer_.

North and south, the island was fringed