"Oh, how I detest that chap!" grumbled Poole to Plum, one night when they were alone. "Gus, we must get square."
"That's right," returned the bully. "But not now. Wait till he is off his guard, then we can fix him, and do it for keeps, too!"
On the following Saturday evening Chip Macklin called Dave to one side. The young student was evidently excited over something.
"What is it, Chip?" asked Dave. "Hurry up, I can't wait long, for I want to join the fellows in the gym."
"I want to tell you something about Gus Plum," was the answer. "I think I've discovered something, but I am not sure."
"This afternoon I got permission to ride over to Rockville on my bicycle, to get some shirts at the furnishing store there. Well, when I came out of the store, I saw Gus Plum coming out of the post-office on the opposite side of the street. He had some letters in his hand, and he turned into the little public park near by, sat down on a bench, and began to read them."
"Well, what is remarkable about that, outside of the fact that he is supposed to get all his letters in the Hall mail?" remarked Dave.
"That's just it. I made up my mind something was wrong, or else he'd have his mail come here. I saw him tear three of the envelopes to pieces and scatter the bits in the grass. When he went away, I walked over to the spot and picked up such bits of paper as I could find. Of course, you may say I was a sneak for doing it, but just look at what I found."
"I have no desire, Chip, to pry into Plum's private affairs."
"Yes, but this is not his private affair--to my way of thinking. It concerns the whole school," returned Chip Macklin, eagerly.
Dave glanced at the bits of paper, and at once became interested. One piece contained the words, "Stamp Dealer"; another, "Rare Sta-- w York," and another, "Stamps Bought and Sold by Isaac Dem-- --nett Street, Sa----"
"These must have come from dealers in stamps," said Dave, slowly.
"Did you ever know Gus Plum to be interested in stamps?"
"I don't know. Strange as it may seem, I couldn't find any of the written-on portions of the envelopes."
"Not until later--when I was on my way back to the Hall."
"Nothing. He acted as if he wanted to avoid me."
After this the pair talked the matter over for several minutes, but could reach no satisfactory conclusion regarding the bits of paper.