eturn from the
gunnery range."

"Do you think this sabotage is the work of an enemy agent?" Hartson
Brant inquired.

John Gordon shrugged. "Perhaps. Yet we don't really think so. In the
first place, an enemy agent would probably not leave a calling card. And
second, we're reasonably sure no agent could have gotten past the
security check."

There was silence while Scotty and the Brants thought over what Gordon
had said. The scientist busied himself with the excellent food, and
finally accepted a cup of coffee.

Rick voiced aloud the angles that puzzled him the most. "If not an enemy
agent, then why the sabotage at all? Who would have anything to gain but
an enemy?"

"If we had the answers, we could find the saboteur," Gordon pointed out.
"If we knew why he calls himself 'The Earthman' we might also have a
lead. But as it is, we're stumped. It could be anyone on the base,
including me."

"Is it you?" Barby asked in a stage whisper.

Gordon looked around, as though to make sure there were no
eavesdroppers. "I don't think so," he whispered, "but I'll have to admit
I haven't looked since yesterday."

"What do you want the boys to do?" Mrs. Brant asked.

The scientist became serious again. "It's a desperate hope," he
admitted, "but there is always a possibility they might turn up
something if we plant them as undercover agents. Rick and Scotty not
only have good sense, but they're lucky. Maybe they'll be lucky enough
to stumble over or sniff out a lead."

"How do we do this?" Rick wanted to know. He was definitely interested
in the job. Just the idea of witnessing a big rocket shoot was exciting
enough, even without the added attraction of a saboteur to be uncovered.

"You get jobs," Gordon stated. "But you'll have to get them on your own
merits, because if I intervened in your behalf that would be a tip-off.
Only I and the Chief of Security will know about you."

"Can you trust the Chief of Security?" Barby asked.

Gordon smiled. "A fair question. All I can say is, trust must start
somewhere. If Tom Preston is the Earthman, I'll turn in my spaceman's
suit and proton disintegrator and resign from the human race."

Rick grinned. "All right. We'll trust the Chief of Security on your
say-so. What's the next step?"

"Well, you're not old enough to have much of a work history, so we'll
have to exaggerate your ages and the time you've worked. It will be safe
enough, so far as being found out is concerned," Gord