"And I'll lock the back one!" said Bert.

The man, who had heard Frank's call from behind the pile of boxes, must have known something had gone wrong with his plan to cheat.

"Never mind about the b.u.t.ter," he said quickly. "I guess I won't buy any after all. Just give me back my twenty dollar bill, and I'll get along."

"Oh, no, you won't!" exclaimed Harry, as he slipped around some barrels. Quickly running to the front door, the country boy locked it, and stood in front of it.

"Hurry! Give me my money back, I tell you!" cried the man to George, who stood near the cash drawer, not knowing what to do.

"Don't you give it to him!" advised Frank, stepping out. "Lock the back door, Bert," he called.

"I have!" cried the older Bobbsey boy.

The man started to run behind the counter, to find a way out, but he was too late. Bert had locked the door, and taken out the key.

"Let me out of here!" cried the stranger. "Let me out!"

Bert and Harry were somewhat frightened, but Frank was brave.

"You don't get out of here until you pay back the twenty dollars you cheated out of Mr. Mason," he said.

"I don't know anything about any Mr. Mason!" the stranger said. "I want my twenty dollar bill back, I won't need any b.u.t.ter to-day!"

"Don't give him that money!" cried Frank to George. "It's bad, and if you give it to him, he'll try to cheat someone else with it."

"I'll fix you!" cried the man. But at that instant there was a rattling sound at the front door, and Harry, looking through the gla.s.s panels, saw Mr. Mack, the store owner, and two or three other men outside.

"What's the matter? What has happened? Why am I locked out of my own store?" cried Mr. Mack, rattling the k.n.o.b.

"There's a cheat in here!" cried Harry, unlocking the door. "There he is!" he went on, as Mr. Mack rushed in. "That man tried to pa.s.s a bad twenty dollar bill on your boy," went on Harry.

"He did, eh?" cried Mr. Mack. "Well, I'll see about that!"

"You let me go!" exclaimed the strange man. "I haven't done anything.

I wanted some b.u.t.ter, but I changed my mind. There isn't anything wrong in that. Give me my twenty dollar bill and I'll go!"

"Oh, no, you'll not--not until you explain," said Mr. Mack, and he caught the man by the arm. Then the man tried to break away.

"Here, help me hold him!" Mr. Mack called to some of his friends who had come in with him. "We'll see what this is all about. Who can explain?" he asked, looking at Bert, Harry and Frank, in turn.

"He can," said Bert, pointing to the former circus boy.

At this the stranger took a good look at Frank, and he seemed much worried.

"I see you know me," said Frank with a smile.

The man muttered something to himself.

In a few words Frank told how he had been cheated by the old twenty dollar Confederate bill the man had pa.s.sed on him some time ago, in the lumber office.

"And when I saw that man, to-day, for the first time since, hiding around your store," went on Frank to Mr. Mack, "I thought perhaps he was up to some of his old tricks. He went in as soon as you went out, and I saw him give your clerk the same kind of a bad bill he gave me.

Only I gave him eighteen good dollars in change."

"But I didn't," said George Smith with a grateful look at Frank. "I was warned in time."

"I tell you it is all a mistake," said the man. "You had better let me go."

"The only place you will go to is prison," cried Mr. Mack. "Take him away, Constable Sprigg," he said to one of the men who had come into the store with him. "Take him away!"

So the man who had cheated Frank, and who had nearly cheated Mr.

Mack, was locked up in jail. It was found that he had many Confederate bills with him. That money was once good in the Southern States, during war-times, but now it is of no value, and will not buy even a stick of candy.

Of course grown persons could not be fooled by the Confederate bills, but boys, who had never seen any of that money, might be easily deceived. And it was on boys that the man played his tricks, giving them bad twenty dollar bills for some small purchase, and getting good money in change.

"He just waited until Mr. Mack went out of his store," explained Frank, "and he knew only a boy was left in charge. That's how he tricked me, waiting until Mr. Mason was out of the office."

"Well, you did me a good service," said Mr. Mack, "and if ever you are in need of work, I'll give you a place in my store to help George when I am out."

"I guess Frank is going back in the lumber business," said Bert.

The next day Mr. Mason came in answer to the letter he had received about Frank. He brought with him the bad twenty dollar bill the man had cheated Frank with, and a little later the dishonest man was taken away by a policeman, and put in a place where he would have to work hard as a punishment for cheating honest persons. The Bobbseys never saw him again.

Everyone said Frank was very smart to catch the cheat as he had done.

Mr. Mason received back his twenty dollars, for the man had some good money in his pockets when arrested.

"And now are you ready to come back with me, Frank?" asked Mr. Mason, when everything had come out right.

"I--I guess so," was the rather slow answer.

"My girls are anxious to see you again," the lumber merchant went on.

"They have missed you very much. And I want to say I am sorry I was so cross and severe with you," he added. "I was provoked that you should be cheated, but I realize now that it was not your fault. That man made it his business to fool boys with his bad bills. Will you come back, Frank? I promise to treat you better from now on."

"Yes, he will go back," said Uncle Daniel, "but he hasn't had much fun this summer. Suppose you leave him here at Meadow Brook for a while. I think it will do Frank good."

"All right," agreed Mr. Mason. "But my wife and the girls are anxious to have him home. But let him stay here for a time."

And so happy days began for Frank Kennedy, and the happy days continued for the Bobbsey twins, and their friends and relatives. The long summer days on the farm were filled with good times.

One morning Freddie and Flossie went out in the kitchen where Dinah and Martha were busy making sandwiches and wrapping cakes in waxed paper.

"Are we going to have company?" asked Flossie.

"We's gwine t' hab annuder picnic!" exclaimed Dinah. "A big one!"

"Oh, goodie!" cried Freddie. "And I'm going to take my fire engine to the woods and squirt water on snakes."

"Well, don't pump any fire engine watah on ole Dinah, honey lamb!"

begged the fat cook.