“The very thing,” replied the secretary. “Of course I need not impress upon you the importance of absolute secrecy in this matter. We have almost positive proof that our every movement is watched by agents of those who have stolen the plans, and who now have Lieutenant Chapin a prisoner – that is, if they have not made away with him, poor fellow. My own idea is, however, that he has been kidnapped and forced to take charge of the work, as without his direction it would be impossible, even with the aid of the formula, to manufacture the explosive. What I fear is, that after they have made a sufficient quantity to stock up the arsenals of the far Eastern power they will destroy their plant and end Lieutenant Chapin’s life. You see the explosive is so powerful that even a small quantity would make the nation possessing it extremely formidable, therefore it is not likely that wherever they have set up their plant they are figuring on a permanent location.”
“What is the last trace you have of the plotters?” asked Frank.
For answer the secretary pressed a bell that stood on his table at his elbow. When in response the bowing old negro appeared he said sharply:
“Send Flynn here.”
Flynn turned out to be a thick-set, red-faced man with the neck of a bull and powerful physique. He was one of the most trusted men in the Secret Service Bureau.
“Flynn,” said the secretary when the detective had introduced his huge bulk, “these young men are Frank and Harry Chester, the Boy Aviators, they are going to take up your work where you left it off.”
“Only because we were up against a dead wall,” protested the agent.
“Quite so – quite so; I meant no offence. I know that you did all it was humanly possible to accomplish. What I want you to do now is to outline to these young men the discoveries you made following the morning on which we found the safe opened and the plans gone, – to be followed a few hours later by the discovery that Lieutenant Chapin had also vanished.”
“Well,” said Flynn, “cutting out the minor details we discovered that the very same day a big white yacht had cleared from New York without papers and had headed toward the south. We traced her up and found that she had been bought by a Mr. Brownjohn of Beaver Street. We looked him up and found he was a ship broker who had bought the craft on telegraphed instructions from Washington. We trailed up the telegram and found that it had been sent from the Hotel Willard by a Captain Mortimer Bellman, who, from what we can find out about him, was considerable of an adventurer and had at one time lived a good deal in the far East. In fact he had only recently come from there. At the Marine Basin at Ulmer Park, near Coney Island, we discovered that a nondescript sort of a crew had been hustled on board and that the yacht had sailed at night without papers a few hours after her purchase was completed.
“Ten days later the newspapers reported that a large yacht had gone ashore on one of the Ten Thousand Islands on the west coast of the Everglades, and the men we sent down there to investigate discovered that the derelict was the Mist, – the same yacht that Bellman had bought. What was most remarkable, however, was that the boat seemed to have been deliberately wrecked, for everything had been taken off her except her coal and ballast and all the boats were gone. There was no indication that she had been abandoned in a hurry and the reef on which she lay was such an obvious one that even at high water it was clearly visible. Now that the Mist’s boats went into the Everglades we are reasonably sure. If they had gone anywhere else we should have got some trace of them by this time, but from that day to this we have not had a word or sign concerning them.”
“We have heard, however, that the navy of the power we suspect has been conducting experiments with a new explosive and we have also learned that this same explosive is undoubtedly Chapinite. We have looked up Bellman’s record and find that while he was stopping at the Willard he received several letters from the government in question and that he paid twenty thousand dollars for the Mist. Now a man isn’t going to pay that much out for a boat and wreck her unless he does it purposely. Bellman didn’t have that much money anyhow. There is only one conclusion, Bellman was simply the agent for some one else and that some one has got a lot of money to spend to secure the most powerful explosive ever discovered.”
“There you have the case in a nutshell,” remarked the secretary as Flynn concluded.
“There is only one thing that is not clear to me,” objected Frank. “Why should they make the stuff in the Everglades. Why not manufacture it out and out in the country you have mentioned?”
“Such a course would have been too full of risks,” replied the secretary, “we are at peace with that power and if the stolen formula had been discovered there it would have led to a serious international breach and possibly war. By manufacturing it here and shipping it secretly in small quantities the plotters secure safety from war to their own country.”
“I see,” nodded Frank. He pulled out his watch. It was twelve o’clock. “There is a train to New York at one o’clock,” he said.
“Won’t you stop and have lunch with me?” asked the secretary.
“No, thank you,” was the boys’ reply; “you see we have a lot of work before us. Building an aeroplane in three weeks calls for some tall hustling.”
CHAPTER II
THE BOYS MEET AN OLD FRIEND, – AND AN ENEMY
As the boys hurried from the office of the Secretary of the Navy they almost collided with a plump faced, spectacled young man in an aggressively loud suit of light summer clothes who was just rushing in.
“I say, look out where you are coming, can’t you?” he was beginning when he broke off with a cry of delight.
The next minute the boys were wringing the hand of Billy Barnes the youthful newspaper reporter who had been with them in Nicaragua and whose life they had saved when he was a captive among the Nicaraguans. Boy fashion the three slapped each other on the back and went through a continuous pump-handle performance at this unexpected meeting.
“What on earth are you doing here?” asked Harry when the first enthusiasm of the greetings had worn off.
“Working,” replied Billy briefly. “I’m on the Washington Post.”
“But I thought you were going to take a holiday after you had realized your money on the sale of your share of the rubies we found in the Toltec cave;” said Frank wonderingly.
“Well,” rejoined Billy, “of course the money I got for my two rubies looked good and it feels pretty nifty to have a check-book in your inside pocket; but I guess I can’t be happy unless I’m working. I bought my mother up the state a pretty little place in Brooklyn and tried to settle down to be a young gentleman of leisure but it wouldn’t do. I wasn’t happy. Every time I saw the fire-engines go by or read a good thrilling story in the paper I wanted to be back on the job, so I just got out and hustled about for one and here I am.”
“But what are you doing at the office of the Secretary of the Navy,” demanded the boys.
“Ah, that’s just it,” rejoined Billy mysteriously, “I’m on the track of the biggest story of my career and I think it’s a scoop. Can you fellows keep a secret?”
“We can do better than that,” laughed Frank, “we can tell you one. What would you say if we could tell you your errand here?”
“That you are pretty good mind-readers,” retorted Billy promptly. “I can guess yours though. You are here to try to sell the government an air-ship.”
“Wrong,” shouted Frank triumphantly. “But you – William Barnes – ” he went on, making a mysterious pass at the other boy’s head, “you are here to find out about Lieutenant Chapin.”
“How on earth did you know that?” gasped Billy, “you are right though. Do you know anything about it?” he inquired anxiously.
“Everything,” replied Frank.
“Oh, come off, Frank,” retorted Billy, “that’s too much. How on earth can you – ?”
“That