"If we could only find the one who did it!" It was on Bet's mind continually and finally she went to Principal Sills and talked the matter over with him. What she suggested was a trap to catch the one who had played such a mean trick on her friend.
"Whoever owns that book wants it back worst way or she would never have bought it. If we put it on Miss Owens' desk, sooner or later the guilty one will try to get it. No one else will want to touch it."
Mr. Sills was rather skeptical about the success of the plan.
"We can try it, anyway. I'm always here until after the school is locked at night."
Miss Owens was taken into the secret between Mr. Sills and Bet, but no one else was told about it.
"I can't even tell you Merriweather Girls," confided Bet. "But I'm sure I'll be able to tell the whole story before long, and you'll all be glad."
And the girls feeling sure that it had something to do with Kit's trouble, did not urge her to confide in them.
Bet, in a quiet way, saw to it that everyone in the class knew that the key book was on Miss Owens' desk.
And her three chums found Bet a very unsatisfactory companion for the next few days. Every night after school she excused herself by saying that she had to see Mr. Sills. If they could have seen her hiding away in one of the lower grade rooms where she could see the only unlocked door of the building they would have wondered what she was up to.
On the third afternoon she was rewarded. Just as she was about to give up and go home, she saw a figure dart around the building and come in the door.