"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 the next algebra test. Sluper, we've a thief right here in Rally Hall."

"I'd be sorry to think that, sir," said the dismayed janitor. "I can't think of any of the boys who might do such a thing."

"But some one of them did, just the same," replied the professor. "See here," and he showed the janitor the shaving of wax.

"That proves that it was all planned beforehand," he said. "An outside thief would have had a skeleton key, or simply pried it open with a jimmy. But somebody has taken a wax impression of the lock and had a key made to fit.

"Keep this thing perfectly quiet for a time," the teacher cautioned. "Be on the watch for anything suspicious you may see or hear among the boys.

And I want you to go down town to Kelly's, the locksmith. Get into a talk with him, and bring the conversation round to the subject of duplicate keys, and how they're made. If he's done anything of that kind lately, he may drop a hint of it. He'd have no reason to keep quiet, for he's an honest man and wouldn't do a crooked thing. If he's made such a key, the thief has given him some plausible reason for getting it made.

Find out anything you can, and let me know at once. But, above all things, don't let the matter get out."

The janitor, badly confused, went away on his mission, while Professor Raymond sought out Dr. Rally to lay the matter before him. If it had been an ordinary case, he would have acted on his own discretion. But this was altogether too serious, involving as it did the good name of one of the scholars, and, to a certain extent, the reputation of the school itself.

He found the doctor in his office, and laid the matter before him, giving him all the details that he knew himself and telling of his instructions to the janitor.

Dr. Rally was white hot with amazement and indignation.

"The rascal shall suffer for it if we catch him!" he announced, with a grimness that would have delighted Aaron Rushton and confirmed him in his admiration for the doctor's sternness. "I'll dismiss him. I'll disgrace him. I'll make such an example of him that nothing of the kind will ever happen in this school again."

His eyes flashed under his s.h.a.ggy brows, and the fist he brought down on the desk clenched till the knuckles showed white.

"But what could have been the motive?" he asked, as he grew more composed. "Of course, we can understand why some one might want to know the questions that were going to be asked. But why did they take the whole package? One slip would have done as well as fifty. Then, too, they might know that if the whole package were taken, you would simply call the examination off, as soon as you had missed them, and make out a new set of questions. Then they'd have had all their trouble and risk for nothing."

"It is curious," answered Raymond. "If the idea was simply to get advance information to help some boy through with the test, the only way to do it was to take one copy and leave the rest of the slips there, trusting me not to notice that the package had been tampered with.

"My theory is that he meant to do this, but perhaps was frightened away by some sound, and didn't have time to do it. In that case, he may take out one of the slips and try to put the package back to-night. The examination doesn't take place till day after to-morrow, and he may figure that I haven't missed them. As a matter of fact, it was only by the merest chance that I did miss them to-day."

"Well, let us hope that he will try it," said Doctor Rally. "We'll have Sluper stay in your office all night and nab him if he comes."

Sluper came back from his trip to town and reported that Kelly knew nothing of the matter. Nor had he heard of anything among the boys that might throw light on the mystery.

He kept a careful watch that night in Professor Raymond's office, but without result.

The next day there was something in the atmosphere of Rally Hall that made every one feel that a storm was brewing. The air was electric with signs of trouble. Nothing had been allowed to leak out, but any one could see that something was the matter, though without the slightest idea of what it was.

Doctor Rally was more snappy and gruff than they had ever seen him, and Professor Raymond went about his work in a brooding and absent-minded way, that, with him, was most unusual.

"What's come over Raymond to-day?" asked Fred. "He looks as though he were going to the electric chair."

"He certainly does have plenty of the gloom stuff," agreed Billy.

"Off his feed, perhaps," suggested Slim, to whom nothing seemed more tragic than a loss of appet.i.te.

"Into each life some rain must fall, Some days be dark and dreary,"

quoted Tom.

Fred laughed and made a pa.s.s at him, little thinking how soon the lines would apply to himself.

In his mail that afternoon, the professor received a letter. There was nothing about it to identify the writer. In fact, there was no writing, as both the address and the letter itself were printed in rough, sprawling letters. It read this way:

"Look in Fred Rushton's locker."

The professor was thunderstruck. For several minutes, he sat staring at the printed words without moving a muscle.

The first shock of amazement gave place to a sharp, gripping pain.

It could not be a coincidence. In the present condition of affairs, this mysterious note could refer only to one thing--the missing slips of the algebra test.

Fred Rushton! He, of all boys! Why, he would almost have been ready to stake his life on the lad's honesty. He was so frank, so square, so "white." The professor had grown to have the warmest kind of a liking for him. In study and in sport, he had stood in the first rank, and so far there had not been the slightest stain on his record.

No, it could not be possible that he had done this dastardly thing. He was almost tempted to tear the letter up.

And yet--and yet----

He _must_ make sure.

He went to the office of Doctor Rally. From there, after a short conference, he went in search of Fred.

"Would you mind letting me take a look at your locker, Rushton?" he asked carelessly.

"Why, certainly not," answered Fred promptly, but wonderingly.

They went to the dormitory which at that hour was deserted.

"Here you are, Professor," he said, opening the locker.

There were some clothes lying there, neatly folded. The professor picked them up.

There, with the seals still unbroken, lay the missing package!

CHAPTER XXIV

A PUZZLING CASE

Professor Raymond picked the package up and examined it carefully. There was no sign of tampering with the seals. It was in precisely the same condition as when he had received it.

"Well," he said, as he looked coldly and accusingly at Fred, "what have you got to say?"

Fred was looking at the package with wide open and horrified eyes. He groped for words in his bewilderment, but his tongue seemed unable to utter them. The silence grew painful.