Mr. Swenson was escorted to the State Police car. Before the troopers started off, they again cautioned George to drive ahead slowly.

"For two cents I would step on the gas and try to get away!" she fumed to her companions.

"I wouldn't advise it," Bess said uneasily. "We're in enough trouble now."

"Oh, Bess! I was only kidding," George retorted.

The three girls fell into gloomy silence. The prospect of unpleasant notoriety for their families was anything but rea.s.suring. The friends were glad that at least they had been permitted to drive a short way ahead of the police car, for their entry into Mapleton attracted less attention than would otherwise have been the case.

When they reached headquarters and parked, Nancy warned, "Whatever happens, don't say anything that will incriminate Joe Swenson!"

Outside the building, the girls were confronted by the two men they had overheard talking in Stanford.

"This is our man, all right!" one of them said as the troopers' car bearing Joe Swenson pulled up. The inventor was hustled out, and into the custody of the men.

"Trying to help Swenson make a getaway, eh?" the other of the pair accused the girls. "Come along, you three!"

"Plain-clothes detectives!" Nancy murmured.

As they went up the steps, George teased, "What would Ned Nickerson think if he could see his Nancy now!"

"If it comes to the worst, we can call on him." Nancy smiled. "Before we're through, you may be glad he is my friend!"

Inside headquarters, the situation lost all suggestion of humor. Here Nancy and her friends were told by Police Captain Johnson that the detectives had learned at the plant of Joe Swenson's departure in a car bearing Nancy's license number. He made no reference to the detectives' source of information. To the girls' dismay, the inventor was booked on a charge of arson.

No charge was placed against them, but the girls were asked a great many questions, and their names and addresses were written down. When Nancy gave hers, significant looks were exchanged among the captain and the detectives, Davil and Rock. After that, the girls were treated less peremptorily.

But if they had hoped that the name of Drew would release them at once, Nancy and the cousins were disappointed. They were informed that they must submit to further questioning.

George and Bess were thoroughly frightened and Joe Swenson had become so agitated that he could not speak in a normal tone of voice. Nancy realized that he was in no condition to defend himself. The four were given chairs opposite the two stern-faced detectives and their captain.

One could have heard a pin drop, the room became so quiet. The officers stared fixedly at Joe Swenson, who squirmed uncomfortably in his chair. Suddenly Detective Davil pointed an accusing finger, and his voice rasped out so sharply that Nancy jumped.

"Swenson, when did you first plot the death of Felix Raybolt?"

"When did I-I don't know what you mean," Mr. Swenson stammered.

The keen glance of his questioner did not waver.

"You know well enough what I mean. It won't do you any good to try to lie. You were seen near the Raybolt estate on the day of the fire."

"Who says I was there?" Swenson demanded. "You're accusing me because you can't find the real criminal!"

His shot went home, for the detective blinked, briefly nonplused. But he went on, "You were seen by the railroad station agent, and as soon as he identifies you, we'll have you behind bars. Now out with your story! It will go easier for you if you make a complete confession."

"There's nothing to confess," Swenson returned bitterly. "I did go to the Raybolt estate-"

Nancy's heart began to pound. Was the inventor going to confess something he had not told her?

"So!" his questioner cried triumphantly. "Then you admit going to the house!"

"I've admitted nothing damaging!" Swenson retorted hotly. "I went to the house because I had an appointment with Felix Raybolt."

Nancy was sure now that Swenson intended to make a clean breast of everything; and while admiring his honesty, she realized that he was apt to make his case appear worse than it might be. She longed to warn him to remain silent until he could consult a lawyer.

Bess and George sat transfixed.

"So you had an appointment with Raybolt, eh?" Detective Rock took up the questioning. "What kind of appointment?"

"He had a patent of mine and I wanted him to make a settlement."

"Raybolt owed you money?"

"Yes. He stole my invention. I wanted either the money, or my drawings back."

"What did Raybolt say?"

"I never saw him. There were no lights in the house. He didn't answer the bell. Then there was an explosion and I ran away."

"You knew he was in the house and you didn't try to save him?" the captain interjected.

"I don't believe he was in the house!"

"When did you last see Raybolt?"

"In a restaurant here in town."

"I see," Detective Davil observed with satisfaction. "You had an argument, didn't you?"

"Yes," Swenson admitted unwillingly, "we did have hot words."

"Which ended in a threat from you," the officer concluded.

Joe Swenson shook his head vehemently. "No, I swear it! I'll tell you everything-right from the very beginning. Raybolt seemed uneasy, as though he were afraid I'd attempt physical violence-he had a guilty conscience, all right!"

"You argued about the invention?"

"Yes. He admitted he had deliberately stolen my ideas, but he defied me to prove anything. That made me angry."

"You threatened him?"

"I told him I would take the matter to court. Of course I didn't have any money to engage a lawyer, but my bluff frightened Raybolt and he told me to come to the house where we could talk privately."

"What do you think caused the fire?" the captain asked.

"The explosion-which nearly knocked me off my feet. I was sort of dazed for several minutes-"

"What happened next?"