“Pulter’s book, eh?” murmured Mortimer, slowly, as he turned it about, looking on the front and back blank pages.

“It sure is,” went on Andy, eagerly. “I’d know that ink blot anywhere. Pulter let out a howl like an Indian when my pen leaked on his book. The blot looks like a Chinese laundryman turned upside down.”

“That’s right,” agreed Mortimer. “Queer, isn’t it?”

“Yes,” went on Andy, his curiosity growing. “Where did you get it?”

“Found it,” spoke the rich lad, quickly. “I went out to the new Yale Field to see how the stadium was coming on, and I saw this under a clump of bushes. I knew it was a valuable book, so I brought it back with me. It hasn’t got Pulter’s name in it, though.”

“No,” went on Andy. “His name was on the other front leaf. That was worse blotted with the ink than this one, and he tore it out. But I’m sure that’s Pulter’s book.”

“Very likely,” admitted Mortimer, coolly. “I’ll take it to him. I’m glad I found it. Going my way?”

“Yes,” and Andy walked beside the lad from his home town, thinking of many things. Mortimer went into Wright Hall, but Pulter was not in.

“I’ll leave the book for him,” Mortimer said to Andy, “and you can call his attention to it. If it isn’t his let me know, and I’ll post a notice saying that I’ve found it.”

“All right,” agreed our hero. “But I know it’s Pulter’s.”

He was telling Dunk about the incident, when his roommate came in a little later, and they were discussing the queer coincidence, when Pulter came bursting in.

“Oh, I say!” he cried. “I’ve got my book back! What do you know about that? It was on my table, and——”

He stopped and looked queerly at Andy and Dunk, who were smiling.

“What’s the joke?” demanded Pulter. “Did you fellows——”

“Gaffington found it,” said Andy. “Sit down and I’ll explain,” which he did.

“Well, that is a queer go!” exclaimed Pulter. “How in the world did my book get out to Yale Field? It isn’t so queer that Gaffington would find it, for I understand he goes out there a lot, on walks. But how did my book get there?”

“Probably whoever took it found they couldn’t get much by pawning or selling it, and threw it away,” suggested Dunk.

“Looks that way,” agreed Andy. “But it sure is a queer game all around.”

They discussed it from many standpoints. Pulter was very glad to get his book back, for he was not a wealthy lad, and the cost of a new volume meant more to him than it would to others.

“Well, Andy, how do you size it up?” asked Dunk, when Pulter had gone back to his apartment and Andy and his chum sat in their cozy room before a crackling fire.

“How do you mean?” asked Andy, to gain time.

“Why, about Gaffington having that book. Didn’t it look sort of fishy to you?”

“It did in a way, yes. But his explanation was very natural. It all might have happened that way.”

“Oh, yes, of course. But do you believe it?”

“I don’t know why I shouldn’t. Gaffington’s folks have no end of money, you know. He wouldn’t be guilty of taking a book. If he did want to crib something he’d go in for something big.”

“Well, some of these quadrangle robberies have been big enough. There’s my watch, for instance.”

“What! You don’t mean you believe Gaffington is the quadrangle thief!” exclaimed Andy, in surprise.

“I don’t believe it, exactly, no. If he’s rich, as you say, certainly he wouldn’t run the risk for the comparatively few dollars he could get out of the thefts. But I will admit that this book business did make me suspicious.”

“Oh, forget it,” advised Andy, with a laugh. “I don’t like Gaffington, and I never did, but I don’t believe that of him.”

“Oh, well, I dare say I’m wrong. It was only a theory.”

“I would like to know who’s doing all this business, though,” went on Andy.

“It’s probably some of the hired help they have around here,” suggested Dunk. “They can’t investigate the character of all the men and women employed in the kitchens, the dormitories and around the grounds.”

“No, that’s right. I only hope my friend Link doesn’t fall under suspicion.”

For a week or so after this, matters went on quietly at Yale. There were no further thefts and the authorities had begun to hope there would be no more. They had about given up the hope of solving the mystery of those already committed.

Then came a sensation. Some very valuable books were taken one night from Chittenden Hall—rare volumes worth considerable money. The next morning there was much excitement when the fact became known.

“Now something will be done!” predicted Andy.

“Well, what can they do that hasn’t already been done?” asked Dunk. “They may make a search of every fellow’s room. I wish they’d come here. Maybe they’d find that my watch, after all, has hidden itself away somewhere instead of being taken.”

“They’re welcome if they want to look here,” said Andy. “But I don’t believe they’ll do that. They’ll probably get a real detective now.”

And that was what the Dean did. He disliked very much to call in the public police, but the loss of the rare books was too serious a theft to pass over with the hiring of a private detective.

Just what was done was not disclosed, but it leaked out that a close watch was being kept on all the employees at Yale, and suspicion, it was said, had narrowed down to one or two.

One day Link called on Andy to pay back the money he had borrowed.

“There’s no hurry,” said Andy. “I don’t need it.”

“Oh, I want to pay it back,” said the young farmer. “I have plenty of cash now,” and he exhibited quite a roll of bills.

“Been drawing your salary?” asked Andy, with a laugh.

“No, this is a little windfall that came to me,” was the answer.

“A windfall? Did someone die and leave you a fortune?”

“No, not exactly. It came to me in a curious way. I got it through the mail, and there wasn’t a word of explanation with it. Just the bill folded in a letter. A hundred-dollar bill, it was, but I had it changed.”

“Do you mean someone sent you a hundred dollars, and you don’t know who it’s from?” asked Andy, in surprise.

“That’s right!” exclaimed Link, with a laugh. “I wish I did know, for I’d write and thank whoever it was. It surely came in handy.”

“Why, it’s very strange,” spoke Andy, slowly. “Could you tell by the postmark where the letter came from?”

“It was from New York, but I haven’t a friend there that I know of.”

“Well, I’m glad you’ve got it. Take care of it, Link.”

“I intend to. I can lend you some now, if you need it, Mr. Blair.”

“Thank you, I have enough at present.”

Andy watched his protege walk across the campus, and near the middle observed him stopped by a stranger. Link appeared surprised, and started back. There was a quick movement, and the young farmer was seized by the other.

“That’s queer!” exclaimed Andy. “I wonder what’s up? Link may be in trouble. Maybe that fellow’s trying to rob him.”

The quadrangle was almost deserted at the time. Andy hurried down and ran over to where Link was standing. The student caught the gleam of something on the wrist of his friend. It was a steel handcuff!

“What—what’s up, Link?” Andy gasped.

“Why, Mr. Blair—I don’t know. This man—he says he’s a detective, and——”

“So I am a detective, and I don’t want any of your funny work!” was the snappish retort. “There’s my badge,” and it was flashed from under the armhole of the man’s vest, being fastened to his suspenders, where most plain-clothes men carry their official emblem.

“A detective!” gasped Andy. “What’s the matter? Why do you want Link Bardon?”

“We want him because he’s accused of being the quadrangle thief!” was the unexpected answer. “Stand aside now, I’m going to take him to the station house!”