"Who is he?" inquired Sergeant Riley, noting his companion's astonishment.

"His name is Wernberg," said Mr. Cook.

"I've heard of him," said Riley grimly.

"Have you been looking for him?"

"I know his name," exclaimed the sergeant evasively.

"Well," said Mr. Cook, "he's about done for, I'm afraid. I suppose we ought to get him to a doctor as fast as we can though."

"Yes," agreed Riley.

"I'll get our car," exclaimed Bob.

"Can you bring it in here?" asked his father.

"Yes. I'll have it here in ten minutes," and Bob set off at top speed through the woods toward the spot where the automobile had been left.

Mr. Wernberg was still unconscious. In fact it was difficult for a time to ascertain whether or not he was alive. More water was brought from the spring and Mr. Cook and Riley continued to minister to the sufferer. Some of the worst of his burns were bound up with strips of shirts offered by members of the party, and his outer clothing was removed. As a matter of fact a large portion of it was so burned that it crumbled to powder at a mere touch.

"He's alive," said Sergeant Riley after a few moments.

"Then he ought to recover," exclaimed Mr. Cook. "That is, unless he has inhaled some of the flames and injured his lungs in some way."

"Only a doctor can tell that," said the sergeant. "Whether he gets well or not, one thing is certain and that is he'll be in the hospital a long time."

"That's right," agreed Mr. Cook. "I wish he could talk though."

At that moment Bob arrived with the automobile and presently Mr. Wernberg was lifted into the tonneau and a blanket wrapped around him. He was still unconscious, but his face was drawn with pain that fortunately he could not feel. Much as the men who cared for him despised him for his suspected work with the gang of spies and plotters they could only feel pity for his sufferings.

Mr. Cook, Hugh, and Sergeant Riley accompanied Bob on his trip to the High Ridge Hospital, and the three other members of the party were left to watch the fire and see that it did not spread, and then they were to follow in the other car. Donovan the detective seemed to be himself once more and related briefly the story of how he had rescued Mr. Wernberg.

"I rushed into the house," he said, "and as I stuck my head inside the door a wave of smoke caught me full in the face. At first I expected I should have to turn back, but I kept on and presently the air cleared for a minute. I knew the trapped man was on the second floor so I hurried around looking for the stairs. Finally I found them and though they were awfully rickety I got up.

"The smoke seemed to be thicker on the second floor and I could scarcely see. I heard a cry and followed it, stumbling and falling along the hall. The door of one big room was smashed and the smoke poured out of there as if it was a chimney. No one was in that room and I came out into the hall again. I heard another call, and traced it as coming from a room where the door was closed. I grabbed the door-knob, but it was locked. 'Help! Help!' I heard from inside. 'Unlock the door!' I shouted. 'I have no key,' said the voice, so I put my shoulder to the door and tried to force it.

"I was choking and coughing and gasping, what with the smoke and all, and it was hard work standing there. I shoved with all my might though, and all of a sudden the door gave way. I went shooting into the room and fell right over a man stretched out on the floor. 'They blew me up,' he cried and fainted. Well, the room was full of smoke and all around the edges little tongues of flame were playing; the fellow had fallen to the floor and been terribly burned. I picked him up and staggered out with him and you know the rest."

Donovan himself was badly burned about his hands and face. Every one knows how painful is a burn, but the detective made no complaint, in spite of the fact that he must have been suffering agonies.

Meanwhile Bob was speeding the car back towards High Ridge. He broke all speed laws on the way, but he had been warned that haste was imperative if Mr. Wernberg's life was to be saved. Besides he had a police officer in the car with him and knew that he was safe.

In an incredibly short time he pulled up in front of the hospital. Two orderlies were summoned, and soon Mr. Wernberg, placed on a stretcher, was being carried into the building. Once or twice his eyelids fluttered as though he were about to regain consciousness, but he did not seem to possess sufficient strength to accomplish that end.

Two doctors hastily took him in charge, Sergeant Riley left word that he should be summoned the instant the patient was able to talk, and then Bob ran the car around to police headquarters. Sergeant Riley invited them all into his office and they discussed what their next move should be.

A band passed by the door, several men in uniform followed behind on their way to the city square where they were to make speeches in order to urge more enlistments in the army and navy. Crowds of enthusiastic people trailed the procession, and Bob could not help wondering if the people realized that danger threatened the country from within as well as from without.

Presently the car bearing the three detectives arrived at headquarters. They reported that nearby farmers had come to the scene of the fire, which was now in such condition that no harm could come from it. The farmers had promised to watch over the smouldering ruins, for ruins were now all that remained of the old house.

Donovan once again related his story and then went off in search of a doctor to care for his burns.

"It's bad business, Sergeant," said Mr. Cook.

"It is," Riley agreed. "I'd like to get me hands on some of them fellows."

"Seems queer that they should have blown up one of their own men."

"'Twas probably a mistake. Perhaps they saw us coming and were in such a hurry that our friend Wernberg had no time to get away."

"But look here," protested Bob. "Don't you remember what Donovan said that Mr. Wernberg said when he burst into the room?"

"He said, 'they tried to blow me up,'" quoted Mr. Cook.

"Exactly," exclaimed Bob. "Doesn't that seem queer to you?"

"He was probably left there by mistake, as the sergeant says," said Mr. Cook.

"But," Bob insisted, "the door was locked."

The men looked at one another blankly.

"I had forgotten that," said Sergeant Riley.

"Well," insisted Bob, "I'd like to have that part of it explained to me. You don't suppose for a minute that Mr. Wernberg locked himself in, do you?"

"I shouldn't think he would," Mr. Cook admitted. "But if he didn't do it, who did? That's what I'd like to know."

"Mr. Wernberg wasn't the only man in the house, you know," said Bob.

"Who else was there?"

"Didn't Hugh and two of the detectives chase another man?"

"Yez mean the fake detective?" asked Sergeant Riley.

"I do."

"But wasn't he in the same gang? What use would it be to him to blow up one of his own men?"

"I don't know," said Bob. "Still I don't believe that Mr. Wernberg locked himself in and threw the key out of the window."

"Doesn't sound likely," the sergeant agreed. "I'd like to know why those two men were enemies though. From all I can learn I should think they were working for the same purpose. Why should that fake detective be so eager to get that paper away from yez, and to get you boys away if he wasn't up to something suspicious?"

"Don't ask me," exclaimed Bob. "It's too deep for me, and I get more and more mixed up all the time."

"Well, I believe it's just as I said," continued Riley. "They were both parts of the same crowd. There must have been evidence against them in that house and they wanted to destroy it. Your fake detective blew it up and Mr. Wernberg got caught in there by mistake."

"How do you explain the locked door?" asked Bob.

"I don't, but there must be some explanation for it."

"You think it was an accident, don't you?"

"I do," said Sergeant Riley firmly. "When Mr. Wernberg gets so he can talk I'll bet he'll say the same thing."

Bob merely shrugged his shoulders. He did not think that the sergeant's explanation was correct, but he could offer no better one himself so he said nothing. After all it might be that in the hurry to get away there was a mix up and Mr. Wernberg was left behind, locked in the room. Bob had no doubt in his mind that Mr. Wernberg was a member of a gang that was plotting against the United States. In his heart he felt sure he was guilty.

On the other hand if the fake detective was not equally guilty he would be surprised. Certainly no man would disguise himself in that way who had honorable motives. Nor would any man run away as he had done, or fire a pistol at real officers of the law unless he was engaged in some evil doing.

How were these two men connected? That was the question that bothered Bob. He felt that there was some connection between them, and yet why should one of them be locked in the second story of a house while the other one put a bomb under it and burned it up? Perhaps after all it was as Sergeant Riley had suggested.

"Come on, boys; we'll go home," exclaimed Mr. Cook.

"Thank yez for coming with us," said Sergeant Riley, as Mr. Cook and the two boys rose to their feet preparatory to leaving.

"Not at all," said Mr. Cook cordially. "If there is anything further we can do to help, please call on us."

"I will," said the sergeant. "Thank yez again."

"And don't forget to let us know what Mr. Wernberg has to say."

"I won't."

They went out and got into the automobile and a few moments later were home again.

"After you put away the car, I want you to take a note down to the Wernbergs for me," said Mr. Cook to Bob as he mounted the steps of the house.

"To tell them what happened to Mr. Wernberg?"

"Yes."

"I should think it would be better to go and see them."

"No doubt it would, but somehow I don't like the idea of having to go and talk to Mrs. Wernberg about it. I suppose I'm a coward."

"I don't blame you," exclaimed Bob, and after he had returned the car to its place in the garage he came back to the house to wait until his father should have finished the note he was writing.

When it was ready Mr. Cook handed it to Bob, who at once started for the Wernbergs' house, accompanied by Hugh. They discussed the recent turn of events in the mystery and were somewhat at a loss as to what their next move should be. Now that the old deserted house was a thing of the past they did not know where to look for the seat of the conspiracy. They did decide, however, that in so far as it was possible they would keep watch on number twelve eighty-two Elm Street.

They mounted the front steps of the Wernbergs' house, and Bob advanced toward the door bell. Before he rang it, however, he spied an envelope lying at his feet, half concealed under the door mat. He stooped to pick it up, and as he glanced at it he uttered an exclamation of surprise.

"Look, Hugh," he exclaimed.

The envelope was of plain white paper and addressed to Mr. Wernberg. There was no street number on it, merely the name. This in itself was not particularly odd, nor was it the cause of Bob's surprise. On the other side of the envelope, however, was scrawled a drawing. It was the picture of an alligator.