“I should say it did!” Bob’s voice was eager.  “She took it for the letter ‘B’ and bottle was in her mind.  You may depend upon it, that girl is at the back of all this fuss!  Gee, when I’ve nothing else to do, I’m going to study up on this association of ideas stuff.”

“You don’t need it—­you can get at things without a bit of trouble,” Betty assured him affectionately.

“How will you go about pinning down Ada?” Bob asked anxiously.

“I’ll cut out Latin to-morrow afternoon when she has a study period,” planned Betty.  “She’ll think Libbie is reciting, and she’ll not think of me at all, and I’ll slip out and watch to see if she goes near the bottle.  But what can I do if she does prove to be the right one?  She’ll tell Mrs. Eustice, and poor Libbie will be in a peck of trouble.  I really think Mrs. Eustice would send her home if she knew.”

“And serve Libbie right for being such an idiot!” pronounced Bob severely.  “However, I think she has been pretty thoroughly punished through fear.  I only wish you’d told me this before, Betty, because I know exactly how you can deal with Ada.”

“You do?  Oh, Bob, what should I ever do without you!” cried Betty, forgetting that a few moments before she had berated him for his insistence.  “Tell me, quick.”

“Well, a crowd of us fellows happened to be over in Edentown last Friday night, and we saw Ada and Ruth at the movies,” said Bob.  “They didn’t see us, for we sat back.  They were the only girls from Shadyside, and Tommy and I decided they had sneaked out after dinner and walked all that distance.  Now threatening isn’t a very nice performance, Betty, but sometimes you have to meet like with like.  I think, if when you see Ada digging up the bottle, you go to her and say that unless she returns the money and Libbie’s first note to you and promises to let the matter drop—­forever—­you will expose her Edentown trip to Mrs. Eustice, she will listen to reason.”

“So do I,” agreed Betty.  “I don’t think she has touched the money—­she has plenty.  But I must have the note so that Libbie can destroy it.  Mrs. Eustice never lets us go to town at night, and I’m sure Ada and Ruth had to go down the fire-escape.  Goodness, didn’t they take a chance of being discovered!”

“Well, as I’ve already missed half an algebra recitation, and you know you have no business over here at this time of day, I move we begin our penance,” suggested Bob.  “Paddle home, Betsey, and if our hunch turns out wrong, we’ll tackle another one.”

“Oh, it won’t—­I’m sure you’re right,” said Betty gratefully.  “Thank you ever so much, Bob.  And the next time I’ll tell you everything at the very first.”

“Don’t let me hear of another time,” Bob called after her, with mock severity.

“Well, I never!” gasped Libbie, astonished, when Betty told her of Bob’s suspicions.  “Oh, Betty, wouldn’t it be wonderful if it should be true!”