it works," Scotty said. "You can tell in a movie when they
use it, because the definition of the background isn't as sharp as real
photography, but I didn't know the name of the process."

Scotty turned and studied the location of the port. "He must place the
projector right on the tunnel floor, tilted upward to shine through the
port. That's why the ghost was so tall. It hit the mist at an angle."

Rick bent over the port. "Not hard to smack us in the eyes with methyl
chloride from here, either. There we were, on our knees, faces in good
range. And I'll bet he chuckled while he was doing it. Simple weapon,
too. A water pistol. Or any plastic squirt bottle."

He tugged on the port and it failed to move. Something wrong here. He
studied it carefully and saw the reason. It had to be slid sideways for
a quarter of an inch, a safety-lock feature. No wonder their examination
of the rock face outside had shown nothing.

"Open it," Scotty said. "Let's look."

Rick did so, and instantly closed it partly shut again. "Get down here
and look," he commanded. He had seen at once what had happened during
their absence and his quick mind had caused him to react.

There were men outside, several of them, and they were watching a small
power scoop move into position in front of the lower mine entrance.
Among them were Dr. Miller and Belsely. Away from the group, sitting on
his tricycle scooter, was the Frostola man!

"We forgot about Belsely," Rick said softly. "He saw us, and may even
have seen us go into the mine. Anyway, that's the first place he'd look
when we turned up missing."

Scotty drew back and closed the port gently. "That power scoop can go
right into the tunnel, scoop up a yard of rock and back out and dump it.
It will have the tunnel cleared in no time. We'd better get out there
and let them know we're safe."

"If they were breaking their backs with hard manual labor to get us out
I'd yell through the port," Rick said gleefully. "But they aren't. So
we'll let the scoop operate. It will remove that stuff in an hour. And
when they open up, they'll find us."

Scotty looked at him suspiciously. "The tone of voice tells me you're
whomping up something that will make someone unhappy. What is it?"

"Well, if we rush out and tell the world about this, everyone will know
the ghost is a fake. But that won't help us much, because we'll still
need to know the answer to the biggest question of all. Why do this? So
we go b