When, after parting with Mr. Pauling and the boys, Mr. Henderson drove towards his office, he was in high good humor. The afternoon, thanks to the boys’ radio and Rawlins’ diving suits, had been a most eventful and highly satisfactory one. Not only had the discoveries resulted in the raid on the garage, the seizure of a vast amount of contraband and probably the breaking up of the gang of rum-runners which for so long had baffled his men and himself, but it had brought in two prisoners, one of whom at least he had recognized and was mighty glad to see.

But despite all this he was sorely puzzled and cudgeled his brain to find a reasonable explanation for many things which seemed inexplicable. If, as it seemed, the garage had been a hiding place for smuggled liquor, what connection did it have with the submarine and the divers Rawlins had captured? Had the contraband been brought there in the under-seas boat, and if so how? He knew, as Rawlins had already pointed out, that a submarine could not go in and out of any port—in the West Indies or elsewhere—without attracting immediate attention, for there were not many of the craft knocking about and even if the natives of the islands had kept the secret some of the government’s agents who were scattered through the West Indies would either have seen or heard of the craft. Mr. Pauling, for example, had personally been to Cuba and Nassau and while he had seen schooners leave with cargoes only to return empty without being reported from any American port, still he had found or heard nothing which would indicate a submarine unless, yes, that might be possible—the schooners might have transferred their cargoes to the under-sea boat in mid-ocean or at some uninhabited island.

But even in that case, the native sailors, the mulattoes and negroes, surely would have talked about it. To them, a submarine would have been far too remarkable and interesting a thing not to have told their wondering cronies and families about it. And where, assuming this was so, had the bootleggers secured the vessel?

Rawlins had assured him the submarine was a German U-boat of a recent type, such as had been off the United States coast during the latter days of the war, but she could not be one of these, for the Navy, he knew, had accounted for them all. Had the Germans taken to rum-running? Had they secretly retained one or more submarines, and, knowing the enormous profits to be made, put them to use carrying cargoes of liquor from the West Indies to the United States? Of course this was possible, but somehow Mr. Henderson, who was famed in the Service for his “hunches,” which nine-tenths of the time proved right, had a feeling that there was something deeper, some mystery behind it, and he had high hopes of fathoming this or at least of throwing some light upon it by an interview with the unharmed prisoner.

That he would obtain a confession or even much information from the fellow, he very much doubted, for he knew the man of old—knew him for a sullen, arrogant and thoroughly desperate man and one who could and did keep his mouth shut under the most severe grilling. Mr. Henderson deeply regretted that the other prisoner had been injured by inhaling the flames in his helmet, for with two men, each thinking the other had betrayed him, there would be a good chance of getting at the bottom of things, but it was almost hopeless now. The surgeons had stated that the man was doomed, that he could not possibly survive his terrible burns and that it was doubtful if he ever regained consciousness. Mr. Pauling was to be summoned when the wounded man came to his senses, if he ever did, and in the meantime the other prisoner was to be brought before Mr. Henderson by two of his own men whom he had despatched for the purpose, for, while he and Mr. Pauling coÖperated with the police in many ways, they had no desire to let the police learn of many matters that were taking place or hear statements or confessions which they might repeat.

As soon as Mr. Henderson reached his office, where the erstwhile janitor was on guard, he hurried the latter off and then, taking some documents from a safe and lighting his pipe, he proceeded to study the papers with minute attention. He was interrupted in this by the return of the messenger who was accompanied by a small, wiry, dark-haired man whom Mr. Henderson addressed as “Ivan” and who seated himself in a proffered chair and proceeded to make himself quite at home with an immense black cigar.

“It’s Smernoff!” announced Mr. Henderson presently. “Got him to-day under very remarkable circumstances—no matter what. Recognized him at once although he’s shaved off his beard. Examined his mouth and chest to make sure. I expect him here in a few moments. Do you happen to know if he ever served in the German army?”

“Sure, yes, I know,” replied the Russian. “Not in the army, no, but the navy.”

“What was his job?” demanded Mr. Henderson.

“That I do not know,” replied the other with a shrug of his shoulders.

“H-m-m,” muttered Mr. Henderson. “Well, I want you to be here to interpret. He doesn’t speak much English or won’t. I guess they’re coming now.”

A moment later, there was a rap on the door and the janitor—once more in jumper and overalls—left by another entrance and armed with dustpan and broom proceeded to busy himself in the hallway exactly as if he had not been interrupted several hours previously by Frank’s excited summons to Mr. Pauling.

At Mr. Henderson’s “Come in!” two heavily built men in civilian clothes entered, crowding closely one on either side of the sullen man who had been captured by Rawlins.

Not until they had seated themselves at Mr. Henderson’s orders would any one have suspected that the pig-eyed man was a prisoner or was handcuffed. For a space, Mr. Henderson gazed steadily and silently at the prisoner who returned his stare, hate and venom in his eyes, and then, turning to Ivan, Mr. Henderson ordered him to ask the fellow certain questions.

It is not necessary to repeat the conversation, or rather the queries and replies, and for some time no satisfactory information was brought out, the captive absolutely refusing to admit anything or to say a word which might incriminate himself or his fellows. But when, after a deal of questioning, Mr. Henderson had Ivan hint that the men captured in the raid on the garage had betrayed the Russian and his fellow diver, the man’s face took on a demoniacal expression, his eyes blazed and a torrent of curses and foul oaths burst from his lips.

A moment later, he checked his furious outburst and replied quickly to many of the interrogations put to him through the interpreter.

It was soon evident, however, that he was either extremely ignorant of many matters or else was an accomplished liar, and, while the information he gave cleared up many matters which had puzzled Mr. Henderson previously, still the most important and mysterious features of the whole case remained as much a mystery as ever.

“I guess that’s all we can find out, or all he’ll tell,” declared Mr. Henderson at last. “Take him away and be mighty careful to have him well guarded. He’s a slippery rascal and we don’t want him getting away this time.”

As the men with their prisoner left the room, Ivan rose as if to go.

“Sit down!” Mr. Henderson ordered him. “I may need you again at any minute. We’ve got another man to question yet.”

Ivan’s eyebrows rose in surprise, but he had long been employed as an interpreter in Mr. Pauling’s service and had learned not to ask questions or make comments, no matter how amazing or perplexing a matter might appear. So, again seating himself comfortably, he lit another of his huge cigars and waited patiently and silently for further orders.

Meanwhile Mr. Henderson was going over his hastily written statements of the prisoner and with his knowledge of the man’s past and his “hunch” was striving to dovetail the information with surmises and records so as to form a complete whole.

It was interesting and fascinating work—this building up a case from fragments and conjectures—a sort of jig-saw puzzle with many of the parts missing, and Mr. Henderson was an adept at it. Indeed, he often spent hours, when he had time to spare, playing the game with imaginary or hypothetical cases exactly as a person will play a game of solitaire. It was this ability to piece together stray bits of evidence, and his almost uncanny intuition, that had secured the high position he held and had won the envy and admiration of all in the Service who knew him, although his friends good-naturedly chaffed him about his “imagination,” as they called it.

But on more than one occasion his imagination, or intuition or sixth sense or whatever it might be, had brought most astonishing results; as, for example, the capture of a band of plotters; to which he had referred when discussing the flood of Bolshevist literature and the wave of crime with his coworkers.

Now, as he studied his notes of Smernoff’s statements and at times half closed his eyes as if concentrating on some far-off matter, a smile spread across his features and from time to time he nodded approvingly.

“I’d wager it is,” he commented to himself. “Everything points that way. The submarine, Smernoff—a fanatical socialist—those remarkable deep-sea suits—the under-sea radio, the mystery about it all and yes—the time hitches perfectly. Bloody sort of brute he is—wish I could get him for that—sorry it’s out of our hands. Jove! I hope that mate of his lives long enough to give us what we want. Smernoff admits he knows. By Jove, it would be a coup! Wonder if those boys even dream what their experimenting has led up to!”

He was still deeply engrossed in his occupation when the phone bell rang and Mr. Pauling’s voice came to him. “He’s conscious,” said the latter, “Come to the hospital as quickly as possible. Yes, I’m going this instant. Of course. Bring Ivan.”

“Come along, Ivan!” exclaimed Mr. Henderson, as he hung up the receiver, and grasping his hat he hurried from the room into which the janitor instantly popped like some sort of automaton.

As soon as the ambulance bearing the injured prisoner had reached the hospital, the man had been taken to a private room and the doctors had devoted every attention, every latest appliance, every resource known to modern medicine and surgery to patching the horribly burned and disfigured fellow up in order to prolong his life until he could regain consciousness. In the hospital a more thorough examination had revealed the fact that the interior of his mouth was not so seriously burned as had been thought when first aid was being administered at the dock. Evidently he had had presence of mind enough to snap off the valve and to shut his lips at the first burst of flames from the chemicals when, startled by the submarine deserting them, he had instinctively cried out a warning to his mate and had allowed water to enter the tube.

“There’s about one chance in ten thousand that he may live,” announced the gray-haired surgeon to his assistant. “He has not inhaled flames and it all depends upon his constitution. The shock was enough to kill an ordinary man outright, but it will be no kindness to have him survive. If it were not for Mr. Pauling’s orders I’d take the responsibility of letting him go, I believe. Gad! Can you imagine any one living with a face like that or caring enough to live to undergo the agony that he’ll suffer if he becomes conscious?”

“Not me!” replied the younger man. “I’d think it a Christian act to let cases of this sort find relief in death, but I suppose every man has a right to his life if he wants it. Have any idea why Mr. Pauling’s so keen on having him come to and talk?”

The elder man gazed at his assistant in a peculiar manner.

“No!” he snapped out at last. “And I’m not fool enough to ask or wonder. It’s none of our business and I intend to follow orders to the letter. But you can bet it’s something important. Just peep outside the door.”

With a puzzled expression, the young doctor opened the door cautiously and looked to left and right. On either hand, standing silently, but with watchful eyes, were two heavily built men, dressed in civilian clothes, with soft, dark felt hats on their heads and, even to the intern’s unpracticed eyes, detectives.

“Guess there is something doing,” he remarked as he closed the door, “couple of Bulls out there. What do they think—that he’s going to jump up and run with that face and with both eyes burned out?”

The other glanced up from where he was bending close above the cot and raised a finger for silence. Then, an instant later, he straightened up.

“Get Mr. Pauling at once!” he commanded. “Tell him the man is liable to become conscious at any instant—that he may live, but if he wants to be sure he had better come immediately.”

In the mean time, at the Pauling home, Tom had been relating his story of the strange and exciting events which had taken place under the river.

“Now, Son,” said Mr. Pauling, as Tom had thrown himself upon the lounge in the library while his mother hovered anxiously over him, “if you feel able, tell us all about it. Rawlins told us the main facts while you were getting over your fainting spell, but, as many important matters and far-reaching consequences may result from your discoveries and captures, I would like to know all the details. Just as soon as you feel tired, stop. Your health and welfare are the most important things—everything else can wait if necessary. I would not ask you now, only I know your mother is anxious to hear the story and, moreover, if I am called to the hospital, I would like to have as much information as possible. A lot may hinge on that.”

“Oh, I’m quite all right, Dad,” Tom assured his father. “Of course I’m tired, but I don’t mind talking. In fact I’d like to.”

So, for some time, Tom narrated his adventures, beginning with the descent to test the set at a distance and ending with the crash that sounded in his ears as he was about to emerge from the water and leaving out no detail of his sensations, thoughts or fears.

“I think it’s all quite clear,” declared Mr. Pauling when he had finished. “I’m sorry I cannot divulge everything to you now or explain all the mysteries which surround the astounding discovery that you boys and Mr. Rawlins have made. But later I can and will, as I know you must be dying of curiosity. And I can assure you of one thing: Uncle Sam will be under a great obligation to you and your radio.”

“But you said you’d tell us who the man was whom we captured and what they were doing in the garage,” Tom reminded him.

“Yes, I can do that,” replied his father, “but you two boys must learn to keep secrets and not repeat anything I tell you. The man you and Rawlins brought in—the one who was not hurt I mean—is a Russian, a rabid ‘red,’ and Henderson recognized him and later identified him beyond question by a peculiar tooth and the scar on his chest. At one time he was convicted of a serious crime against our government, but escaped mysteriously from prison. I doubt very much if we get much information from him, as he knows he must serve out his term—with a bit added to it—and he is a close-mouthed rascal. We hope more from his companion, if he recovers consciousness and can talk. If he knows he is dying he may confess at the last minute. As far as the garage is concerned, as you know, we put two and two together and decided the blind sewer had some secret opening in the block where you boys located the mysterious sending set. The fact that both those messages and the conversations you heard under water included the names of flowers convinced us that they emanated from the same source and as Rawlins assured us the conversation in what he called Dutch, but which was probably Russian, came from the men under water, it confirmed our suspicions that the man you boys located was talking to men under water or on the submarine and that somewhere in the block we would find the key to the mystery and more. From what Murphy says, and the appearance of things, we succeeded beyond our expectations. I was afraid that the rascals might have overheard you and Rawlins or that the submarine, which evidently knew that they were discovered, might have warned them. If so, we moved too quickly for them.”

“But are they bootleggers?” asked Frank.

“No doubt,” replied Mr. Pauling, “and many other worse things. When Murphy and Rawlins arrive we’ll probably know more and if the wounded man confesses we’ll solve many mysteries which remain to be unraveled.”

“Well, I’m mighty glad the old under-sea radio worked,” declared Tom, “but I wouldn’t go through that experience again, not for—no, not for Uncle Sam himself.”

At this moment the doorbell rang and a moment later Rawlins dashed into the room, his eyes bright and a happy grin on his boyish face.

“I’ll tell the world it’s great!” he exclaimed, “They got pretty near everything—booze, trucks, men, and that mysterious radio. And a truckload of books and papers—cleaned out a regular nest. That man Murphy is a corker, Mr. Pauling. He said to tell you he’ll be over in a little while. They were just cleaning up when I left.”

Tom jumped up. “Hurrah!” he cried. “Then we were right all along! We always said that fellow was one of a bootlegger gang. Gee, Frank! They can’t laugh at radio or radio detectives now. It wins!”

“I’ll say radio wins!” cried Rawlins.