e all the deeper by contrast with
the moonlight beyond. But Fred could just make out a moving figure
coming down the steps swiftly, and crouching as though to avoid
detection.

At first he thought it was the dog belonging to Big Sluper, the janitor.
But as the figure turned around the corner of the building, he saw that
it was a boy, rather slight in figure. His hat was drawn over his eyes
and his coat over the lower part of his face, so that it was impossible
to recognize him.

"That's queer," mused Fred. "I wonder who he was and what he was doing
at this time of night."

But the floor was cold and his eyes were heavy with sleep, and he did
not debate the problem long. He crept back into the warm bed, drew the
covers over him, and in a few minutes was fast asleep.

CHAPTER XXIII

THE BLOW FALLS

The next day, after school hours, Professor Raymond opened his desk to
get a paper that he wanted. He was about to close it again, when
something in the tumbled condition of its contents, attracted his
attention. He reached sharply over to the lower right-hand corner, and
felt for a package that he knew had been there the day before.

A startled look came into his face, and he felt again more carefully.
Then he hastily took out everything that the desk contained.

He sat down in his chair with a jolt, and a grim expression came into
his eyes. Then he made a painstaking examination of the lock.

It had not been broken, nor was there any other evidence that violence
had been used.

He took out his penknife and scraped the lock. A tiny shaving of
something soft was brought out by the blade, and close examination
showed that it was wax.

He rang the bell for the janitor, and when Big Sluper came in, he
motioned him to a chair.

"Sluper," he said abruptly, "my desk was robbed last night."

"What!" cried Sluper, starting up. "How could that be? Are you sure,
sir?"

"Perfectly sure," replied the professor. "I only wish I were not. But I
had a valuable package in here yesterday, and now it's gone."

"Why, nothing of that kind has ever happened before," said Sluper, much
agitated. "Did the thief take anything else?"

"No," replied Professor Raymond. "And it was no outsider that took the
package. There was a little money in the desk, and any ordinary thief
would have taken that. Besides, the papers that were taken would have
been of no value to any one outside the school. They were the
examination slips for