g this
country," Thurston explained. "But even though we screen them carefully,
a rebel agent like Narko may slip in--usually on a stolen or faked
passport."

When the telecast ended, Tom, Bud, and Ames discussed the news grimly.

"What if Narko has pals working with him?" Bud conjectured.

"If he does," Tom said, "they may try carrying through Narko's mission."

"I'll station extra guards around the outer wall on twenty-four-hour
alert," Ames promised.

Tom approved this measure wholeheartedly, but the purpose of Narko's
secret mission remained a mystery. Why had he tried to force his way
into Enterprises? What was he after? There was little hope of resolving
these questions, since United States Intelligence had learned of the
rebel movement itself only within the past few days. Thurston had asked
Tom and his companions to treat the information as confidential.

"I'd better get back to work," Tom decided after Bud and Ames had left
his office. Tom sat down at his drawing board and began to sketch out
some rough ideas for a vehicle to house the "brain energy" from space.

Tom wondered if the brain would be able to perform actions by itself,
given the proper mechanical output devices. Or would he have to help it
function via an electronic computer to digest incoming information or
stimuli and then to respond through servo controls?

The problem was so baffling and complex that Tom became completely
oblivious to the passage of time. He sketched out plan after plan, only
to crumple and discard each one.

Suddenly a disturbing thought jarred the young inventor out of his
concentration. Perhaps the Brungarian rebel scientists had now figured
out how to decode the radio messages from the Swifts' space friends!

If so, when the brain energy was launched toward earth, they might try
to divert it to their own receiving setup!

CHAPTER IV

ANOTHER TREMOR!

Tom was appalled at this new danger. Shoving his drawing board back into
its wall slot, the young inventor hurried to his desk and made a number
of telephone calls.

Within minutes, a group of five of his most trusted associates had
assembled in Tom's office. First to arrive were Bud Barclay, Ames, and
George Dilling, the Swifts' communications chief. They were joined
moments later by Hank Sterling, the square-jawed chief engineer and
trouble shooter of Enterprises, and Arvid Hanson.

Hanson, a hulking six-footer, made all the delicate scale models of