Rick so much admired. Then he turned his attention
to the ghosts once more.

Rick counted five stops in various parts of the field. After the last
one, the trio turned, recrossed the bridge, moving briskly, climbed the
hill, and disappeared into the cornfield. Mission accomplished,
apparently. What had the mission been?

According to Belsely, this happened each time, except for the occasion
when a cart had been used. What were they hunting? Or, if they weren't
hunting, what were they doing? Rick felt frustrated. To be so close, yet
to be unable to see anything but vague shapes in the darkness!

Tomorrow he and Scotty would search both fields in an effort to find
what the Blue Ghost sought, or to try to figure out what he and his
friends were doing.

Scotty caught up with him as he was crossing the field by his plane. The
dark-haired boy was triumphant. "They had a car, all right, and the
registration was in a container on the steering wheel. I've got all the
dope. Probably I shouldn't have done it, but I sneaked a quick look at
the name. Can you imagine what it is?"

"Jethro Collins?"

"Nope. It's Hilleboe. Dr. Miller's next-door neighbor!"

CHAPTER XIV

The Cold, Cold Clue

The boys were late to breakfast the following morning. They had fallen
into bed, pleased and exhausted, and the noise of the household stirring
had failed to waken them.

Mrs. Miller greeted them as they came downstairs. "I hear you were ghost
hunting again last night. Did you find any?"

"I'll say we did," Scotty replied. "Where is Dr. Miller?"

"Right here," the scientist said from the living-room doorway. "And I
have news for you. Collins called this morning and renewed his offer. I
told him I'd think about it and let him know later. And Steve Ames
called. The powder is definitely carnotite, and it matches ore produced
on the Colorado Plateau. Steve has reported to the Atomic Energy
Commission, and they'll be able to track down its origin without too
much difficulty, since no two ores are precisely alike. Now, how did you
two do last night?"

The two girls came into the kitchen in time to hear the question, and
Rick almost hated to give the answer, knowing that it would disillusion
them, and particularly Barby.

"We trailed three ghosts," he said. "All human."

Scotty added, "And one of them was named Carleton Hilleboe. At least
that was the name on the registration of their car."

They told the story in detail while