CHAPTER VII.

HOW A SECRET PASSAGE WAS USED.

The house was a mouldering mansion of wood, three stories in height, and once a truly imposing specimen of the architecture of the period in which it was erected. Time and neglect, however, had done their work, and it was now dark, unpainted, and forbidding looking, set back, as it was, in a fenced park of several acres in extent. A clump of dark hemlocks surrounded the house, adding to the gloomy note of its unpainted walls, broken shutters and shattered windows, while in the neglected grounds weeds and trailing, unkempt vines ran riot everywhere.

Only to seaward was the place unencumbered by this wild, disordered tangle. In that direction there lay a broad, brick-floored terrace, of immense dimensions, upon which, tradition had it, Marshal De Regny used to strut with a telescope, ever and anon looking seaward for a sight of the expected vessel bearing the rescued captive from St. Helena.

This terrace, the boys were astonished to see, had been recently swept and repaired, offering a broad, smooth floor of considerable extent. At one end, too, stood a brand-new shed, painted green, and quite large. In front, and opening on the terrace, this shed had large double doors. What it housed could hardly be guessed from the exterior. The few fishermen who visited this isolated part of the beach concluded that the green shed must be a sort of boathouse.

The boys, however, basing their conclusions on the conversation they had overheard a short time before, decided that the airship, or aeroplane, or whatever kind of aerial craft it was, with which experiments were being conducted, must be housed within this shed.

Suddenly they saw a slender, erect figure, clad in the uniform of an officer of the United States Army, crossing the rough lawn lying between the house and the bricked terrace.

“It’s Lieutenant Duvall!” exclaimed Rob, hastening forward, followed by the others. The officer presently spied the intruders, and stopped short, with an angry expression on his countenance as he did so.

“You boys must keep off here!” he ordered, coming toward them. “This is now government property.”

“We’ll get off it in just five minutes,” answered Rob, somewhat abashed at this reception, “but in the meantime I’ve something to tell you of great importance. It hasn’t to do with the Moquis, either,” he added mischievously.

At these words, a great light seemed to break over the officer. In the nattily-uniformed boys before him, it was no wonder he had not sooner recognized the lads he had last seen in tattered, worn, cowboy rig-outs, stained with powder, and worn by a hard chase across the mountains to the Moqui valley.

“Why!” he exclaimed, his manner changing, and both hands extended in a cordial way, “it’s the young broncho busters! Hull-lo, boys! I’m glad to see you again. But what are you doing in this part of the country?”

“We happen to live here,” rejoined Rob demurely, after the first greetings had been exchanged.

“That’s so. You did tell me, I remember now, that you lived here. That must have been your father I saw last night. Very forgetful of me, but I’ve had so much on my mind lately that I’ve slipped up on a lot of things I should have carried a recollection of. We’re carrying out some big experiments here.”

“Which brings us to what we accidentally overheard on our way out here,” exclaimed Rob. “Is there a man named Dugan detailed to duty here?”

“Dugan? Yes—a most capable man—invaluable to me. Why?”

The officer was frankly astonished, and showed his bewilderment.

As may be imagined, his astonishment not only increased, but became mingled with anger, as Rob launched out into a full and detailed account of all they had overheard.

“The scoundrel,” muttered the officer, gritting his teeth, “and to think that I have regarded him as my most trusted assistant.”

“But he doesn’t know the secret of your equalizer,” ventured Merritt.

“No. Thank goodness, he does not, but,” the officer’s face grew troubled, “I wish I had the plans in a safe place. Somehow, since you have told me all this, I can only regard everybody about me as a traitor. If only I had left the plans with your father to be placed in the safe deposit vault in his bank, my mind would be easy.”

“Then you can work out your ideas without the plans?” asked Rob, in some astonishment.

“My boy, when an inventor has dreamed, and thought and pondered over an idea for many long days and sleepless nights, it is photographed on his brain, and he can never forget it.”

“Then I have an idea!” exclaimed Rob. “Let me take the plans back with me to town. I can hand them over to my father, and he can place them in a vault in the bank.”

“The very thing!” exclaimed the young officer. “I know I can trust you, Blake, and you won’t mind if I give them to you in a sealed envelope.”

“Not a bit,” rejoined Rob. He flushed a bit, though, as he spoke, although the words came readily enough.

“You see,” explained the officer, who had noticed the flush, “I almost dread to let even you have the plans. I cannot bear to let them out of my sight. This Jap—I have a suspicion who he is—is not the only one who is after them for his government. Aerial equipment has now become an important adjunct of every navy and army. In Washington, two attempts were made to get them from me, but in this lonely place I thought I was safe.”

“At least in my father’s bank they will be secure——” began Rob, when he broke off short, and turned swiftly. His keen ear had detected a slight rustling in a clump of bushes behind him. As he communicated his suspicion that some one might have been concealed there, they all sprang forward, surrounding the clump, but there was no sign of a concealed listener, and, satisfied that everything was well, they followed the young officer toward the house. Their conductor narrated, as they went, such details of the experimental work as he thought might interest the lads.

Hardly had they vanished within the gloomy, deserted mansion, however, before two faces appeared above the surface of the ground, peering up from the mouth of one of the concealed passages which Mr. Blake had mentioned as existing on the old place.

Could the boys have seen those two countenances, they would have been greatly interested, for one of them was Freeman Hunt’s and the other was Jack Curtiss’s. To explain how they came to be there, it is necessary to revert for a moment to an occurrence which took place some weeks before on a fishing expedition. Driven by bad weather to shelter in the little cove not far from the De Regny place, the party, consisting of Freeman Hunt, Dale Harding and Lem Lonsdale, had hastily sought a shelter from the pelting rain, as their boat was an open one. In a low, rocky cliff, a half-obscured opening showed.

“Looks like there might be a cave in behind there,” Hunt said, and, on his suggestion, they set to work moving away several big rocks that encumbered the opening. The place proved to be a cave, and an ample one, running back to a great depth, seemingly.

An exploration party had been formed at once, and, after traversing a narrow passage, running back underground for some distance, the lads emerged, to their astonishment, in the clump of bushes in which Rob had just heard the rustling sound.

On this particular day, Hunt and Jack Curtiss had visited the cave alone to explore it more thoroughly. The branch passages they expected to find were not there, however, but, threading the original one, they had emerged into the clump which thickly screened its opening, in time to overhear most of the conversation of the Boy Scouts and the army officer.

As the door of the old house slammed, its echoes reverberating through the tangled, overgrown grounds, Jack Curtiss turned to his companion with a grin of satisfaction.

“Here’s the chance we’ve been looking for,” he exclaimed, wiping the sweat and dirt from his forehead,—for burrowing in long disused passages is dirty work.

“You mean a chance to get even?” asked Hunt in a puzzled tone.

“Yes. We can fix that Rob Blake up so that he’ll be in disgrace from this afternoon on.”

“I don’t understand,” rejoined Freeman, who, while he had chosen Jack Curtiss for a companion, had not a tenth part of the other’s evil ingenuity.

“Well, I do,” was the confident rejoinder. “It’s up to us to find this Jap and this Dugan, or whatever his name is. If we can do so, we’ve got Rob Blake where we want him.”

“I see now!” exclaimed Hunt, a light of comprehension showing in his eyes, “but do you dare——”

“Dare!” repeated Jack Curtiss scornfully, “I’d dare do anything to get even with Rob Blake, and,” he added prudently, “the best of it is, that there’s not a chance of it ever being traced to us. If we are only lucky enough to find those fellows they mentioned, they can do the dirty work, and we have the satisfaction of being even with those cubs.”

“But how are you going to find them?” asked Hunt, still hesitating.

“There’s only one road from that hut to this place. We’ll sneak through the grounds while they are all in the house, and nail this chap Dugan in time to put our plan into execution.”

An instant later, two grimy, dust-covered forms emerged from the bowels of the earth, as it seemed, and shoving their way through the dense clump of bushes, glanced cautiously about them.

“Coast’s clear,” announced Jack presently.

Together, Rob’s old enemy and Freeman Hunt, now his equally bitter foe, sped across the De Regny grounds and toward the road.