what?" asked Jeff.

"I--I won't say it," said Strong hesitantly, "but if anything has
happened to those boys, I'll personally dig Vidac's grave!"

Jane had moved to the window and was watching the wild activity in the
Plaza below. "They're spreading out!" she cried. "They must be searching
the city."

Strong rushed to the window and looked down. "That means they haven't
found the cadets!" he exclaimed.

"I've been thinking, sir," said Jeff. "Do you think we really have
enough proof of Vidac's guilt to make the colonists understand it was
Vidac and not the cadets who could have done something to the
professor?"

"We've got to try!" said Strong. "We've got to try!"

The two spacemen and Jane left the laboratory and raced down the
slidestairs and through the halls of the Administration Building to the
double doors that opened onto the Plaza. They stepped into view just as
the colonists were about to spread out and search the city. One of the
men was standing on the steps shouting orders. Jeff recognized him as
Joe, the man who had stopped him on the highway. There was a roar from
the crowd when they noticed Strong, Jeff, and Jane standing in the open
doorway.

Strong held the black journal high over his head and called for order.
The colonists crowded around at the base of the steps not knowing what
to make of his sudden appearance.

"What are you doing here?" demanded the colonist deputy. "You're Captain
Strong of the Solar Guard, aren't you?"

"That's right," replied Strong. "And you're making a big mistake
accusing the cadets of the murder of Professor Sykes, when you're not
even sure the professor has been murdered! The man you want to question
about that is Lieutenant Governor Vidac!"

A startled murmur ran through the assembled men. Strong continued, "I
have absolute proof that Vidac received information about the biggest
uranium strike in the history of the universe from Professor Sykes and
plans to keep it for himself. His accusation of the cadets is a cover-up
to clear himself and to throw you off the track."

The word _uranium_ spread through the crowd like wildfire.

"You're pretty friendly with the cadets," sneered the deputy. "How do we
know you're telling us the truth, and not just trying to save them?"

"Yeah. Answer that one!" roared a voice from back of the crowd.

"Do any of you understand physics?" asked Strong.

"Physics?" asked the deputy. "What's that got to do with it?"

"Plenty!