een eyes saw the first sign, a heelprint in a bare place in
the grass. The boys examined it. "Doesn't match anyone's shoes," Scotty
said. "Not of our gang. Leather heels, a little worn, run down on the
outside edge. You can see the nail marks. No rubber heels would make
those marks."

There were other prints, now that they were searching closely. Clearly,
three men had walked the field last night. But nowhere did they find a
clue to what the men had searched for. There was no raw dirt, no
impressions left where something had been removed.

"Fact," Rick stated. "Three men were here."

Scotty laughed. "This does not mean there were not also three ghosts who
left no tracks."

Rick had to laugh, too. "Now what do we do?"

"Look in the upland cornfield."

They started the survey of the cornfield directly above the mine
entrance, where they had first seen the three ghosts. Tracks were
visible almost at once.

"We're lucky," Scotty said. "Even with the weeds between the rows
there's enough bare ground so we can do some real tracking. Let's see
how the tracks run."

As Scotty had predicted, the tracking was much easier. A few yards into
the cornfield they came to a gap where a few seeds had failed to
germinate or the plants had died. It was a bare space, sparsely grown
with weeds.

Scotty pointed to the three sets of tracks, and put his own feet in one
set, while Rick did the same with another set. From the position of the
third set it was clear that the three men had faced each other.

Rick said excitedly, "They paused and bent over. But over what?"

They scrutinized the ground minutely. It seemed normal enough. There was
absolutely no sign that the earth had been disturbed.

Rick picked up a handful of soil and examined it. "Dirt," he said.
"Plain dirt. Why was it so interesting to the spooks?"

"Try your lens," Scotty reminded him.

Rick did so. The lens showed the usual combination of mineral and
organic matter of various sizes and colors. "I can't see anything
unusual," he reported. "Maybe the lens isn't powerful enough. I'll take
a sample and look at it under the microscope later." He found a scrap of
paper in his wallet and folded a bit of dirt into it.

"Let's continue," Scotty urged.

They worked their way across the cornfield, following the tracks. Twice
more they found places where the ghosts had paused to confer about
something, or examine something.

Then, at the edge of the cornfield, they lo