We must now follow Johnson up-stairs.

In the room above, sitting down tranquilly in an arm-chair, but not in that in the center of the room, was a small, wiry man of unpretending exterior.

"What is your business here, sir?" demanded Johnson rudely.

"Are you the owner of this house?" asked Benjamin Baker coolly.

"Yes. That does not explain your presence here, however."

"I am in search of a quiet home, and it struck me that this was about the sort of a house I would like," answered Baker.

"Then, sir, you have wasted your time in coming here. This house is not for sale."

"Indeed! Perhaps I may offer you enough to make it worth your while to sell it to me."

"Quite impossible, sir. This is my house, and I don't want to sell."

"I am sorry to hear it. Perhaps you would be kind enough to show me over the house to let me see its arrangements, as I may wish to copy them if I build."

"It strikes me, sir, you are very curious, whoever you are," said Johnson angrily. "You intrude yourself into the house of a quiet citizen, and wish to pry into his private arrangements."

"I really beg your pardon, Mr. —— I really forget your name."

"Because you never heard it. The name is of no consequence."

"I was about to say, if you have anything to conceal, I won't press my request."

"Who told you I had anything to conceal?" said Johnson suspiciously.

"I inferred it from your evident reluctance to let me go over your house."

"Then, sir, I have only to say that you are mistaken. Because I resent your impertinent intrusion, you jump to the conclusion that I have something to conceal."

"Just so. There might, for example, be a trap-door in this very room——"

Colonel Johnson sprang to his feet and advanced toward his unwelcome guest.

"Tell me what you mean," he said savagely. "I am not the man to be bearded in my own house. You will yet repent your temerity in thrusting yourself here."

Benjamin Baker also rose to his feet, and, putting a whistle to his mouth, whistled shrilly.

Instantly two stalwart policemen sprang into the apartment from the hall outside.

"Seize that man!" said the detective.

"What does this mean?" asked Johnson, struggling, but ineffectually.

"It means, Colonel Johnson, alias Robert Kidd, that you are arrested on a charge of being implicated in the attempt to steal a parcel of bonds belonging to the National Bank of Chester, Maine."

"I don't know anything about it," said Johnson sullenly. "You've got the wrong man."

"Possibly. If so, you'll be released, especially as there are other charges against you. Guard him, men, while I search the house."

"Here, boy, show me where my young friend is concealed," said Baker to Daniel, who was timidly peeping in at the door.

A minute later and Baker cut the cords that confined the hands and feet of Grit.

"Now," said he quickly, "have you discovered anything that will be of service to me?"

Grit opened for him the dark passage. The detective walked to the end, and saw the room into which it opened.

"Do you know, Grit," he said, on his return, "you have done a splendid day's work? With your help I have discovered the headquarters of a bold and desperate gang of thieves, which has long baffled the efforts of the Boston police. There is a standing reward of two thousand dollars for their discovery, to which you will be entitled."

"No, sir; it belongs to you," said Grit modestly. "I could have done nothing without you."

"Nor I without your information. But we can discuss this hereafter."

Johnson ground his teeth when Grit was brought upstairs, free, to see him handcuffed and helpless.

"I believe you are at the bottom of this, you young rascal!" he said.

"You are right," said the detective. "We have received very valuable information from this boy, whom you supposed to be in your power."

"I wish I had killed him!" said Johnson furiously.

"Fortunately, you were saved that crime, and need expect nothing worse than a long term of imprisonment. Officers, take him along."