The motor-car was approaching the Harlem River. "Your Balaklavan rendezvous is only a few blocks off there," said the agent, pointing to the east.

The car rolled up to the bridge and passed over the dark waters where tugs were shunting car-floats into their docks and churning up white foam with their propellers. Thousands of lights were reflected in the black depths. In a moment the Harlem was behind them, and they were in the borough of the Bronx. On they sped up Third Avenue.

The two boys were distracted. They wanted to see the sights, utterly new to them, and they wanted to hear the discussion of their elders. Willie, with that strange faculty of his for noting places and locations, kept watching the street signs and trying to remember where Third Avenue led to on the map.

"There are three places on Echo Bay where a motor-boat and a motor-car can easily meet," said one of the secret service men. "At the north side of the harbor entrance is a finger of land called Premium Point. On the other shore is Huguenot Park. And an arm of the bay runs inland all the way to the main street passing north through the town."

"Which place would they be most likely to select?" asked Captain Hardy.

"Well, they'd hardly try Premium Point because that is a private estate, and they would have difficulty in getting to the water-front."

"Then that limits them to the two others."

"Exactly. And one is as easy to get to as the other."

Captain Hardy frowned. "What are we going to do?" he asked. "We might pick the wrong place and miss them. And since there are several of these spies in the boat, and they are desperate fellows, we'd never dare divide our forces. What are we going to do?"

"Gee!" said Willie. "We just passed Two Hundredth Street. Some town, eh, with two hundred numbered streets?"

The car rushed on. In silence the three men were considering how they should meet the situation before them.

"If only we could get into touch with our motor-boat," said one of the secret service men, "we could arrange a plan to cover every possibility."

"We've got to find what this Revere Rendezvous is," insisted Captain Hardy. "Can't you think of anything that would suggest such a name?"

The three men fell silent, pondering the matter. The car swept on.

"Hello!" said Willie. "We've left Third Avenue, but we're going so fast now I can't make out the names on the sign-posts."

And indeed they were going. As they approached the edge of the city limits, where there was little traffic and the driver could see far ahead, he pressed his foot on the accelerator and the great car went roaring through the street at more than thirty miles an hour. And as they drew closer and closer to the open country, the man at the wheel rushed them on faster and faster. In vain Willie looked at the sign-posts. The car darted past them with baffling speed. But Willie wanted to know where he was.

"What street are we on now?" he asked, leaning toward the driver.

"The Boston Post Road," said the driver, without turning his head.

Captain Hardy caught the name and his eyes flashed. "The Boston Post Road!" he repeated. "Does this go anywhere near New Rochelle?"

"Right through it," said the driver, "only they call it Main Street within the town limits."

"Does it pass near Echo Bay?"

"It's the very road that meets the arm of the bay."

Captain Hardy turned from the driver to the other secret service men. "Can you think of anything that would connect the name of Revere with the point where the bay touches this road?"

"By George!" cried one of the men. "You've hit it exactly. I had forgotten all about it, but there's a stone marker in a wee bit of a park, put up to commemorate the passage of Paul Revere on his famous ride. He came down this very road, and that marker is almost at the exact spot where the road touches the arm of the bay."

"Good!" said the captain. "That is probably the place."

"Beyond a doubt. It's the logical place, too, come to think of it. For if a fellow drove into Huguenot Park and found that somebody was trailing him, he couldn't get away. He'd be bottled up. But if he stuck to the Boston Post Road, he'd have all New England to run to. What's more, there's a road-house near by, where cars can be left. Things couldn't have been made to order any better."

"Then I guess our course is clear," said the other agent. "We'll leave our car near by and find good hiding-places close to the water at this point."

Meantime, the motor-boat, breasting the waves as though striving for a speed prize, had borne Henry and Roy and their older companions rapidly back over the path they had so recently traversed. Up the East River the craft went roaring, under the great bridges, that at night seemed only strings of fairy lights arching the stream, past prison walls and towering tenements, and on to the swirling rapids so recently visited.

The two boys paid little attention to what they were passing. Already they had seen it twice. But never had either of them seen a craft like that they were in. It was one of those long, low racing boats, steered with a wheel like a motor-car, and slopingly decked over in front to shield the driver. And it roared like an aeroplane as it tore through the water. For the boys in the boat were rushing toward their goal almost as swiftly as their comrades on land.

What most interested Henry and Roy was the array of buttons and knobs and other instruments on the dashboard, like the lighting buttons and speedometer on an automobile.

"I wonder what they are for," said Roy to Henry. "I never saw a boat like this before."

"Nor I, either," replied Henry.

"Right you are," said one of their companions. "There probably isn't another like it. It's both a motor-boat and an electric boat. Sometimes we have to be very quiet about our work and then we would never dare go roaring along as we are now. You can hear us a mile away. So we have an electric motor and storage batteries for quiet work. When we run by electricity, we don't make any more noise than a swan."

The boys expressed their admiration. "And nobody could see you, either," said Roy. "The boat's exactly the color of the water. When it's as dark as this, I'll bet you couldn't see it fifty yards away."

"Well, you may have a chance to test your belief," said the agent with a smile.

"What do you think will happen?" asked Roy.

"I don't know. But when that German motor-boat goes into Echo Bay, we've got to go after it; and we don't dare be seen, either."

"What's the bay like?" inquired Henry.

"It's an irregular little sheet of water with several small islands in it; and if these Germans go clear in, we'll nab them easily. But if they don't, we may have a lively chase."

On rushed the motor-boat. Past Classon Point, past the long projecting finger of land known as Throgs Neck, with Fort Schuyler at its extremity, then northward again into ever widening waters, past Elm Point, and Hewlett Point, and Barker Point until they were fairly in the wider reaches of Long Island Sound.

On the right loomed the high and precipitous shores of Long Island, hardly visible in the cloudy darkness. On the left, far across the waving waters, was the unseen ragged coast of the mainland, broken by a hundred irregular indentations, studded with numberless little promontories, and fringed with islands as a woman's throat is girt with a necklace of beads. Ahead of them stretched untold miles of gently heaving water. And there, too, blazed two beacons to point the path for mariners—the Sands Point Light, topping the eastern bluff, and the fiery eye of Execution Rocks, that reared their jagged pinnacles far out from the shore, to tear the bottoms of unwary ships.

"We'll go straight north," said the man at the wheel, "for those spies are without doubt biding their time in some sheltering cove among the islands over there. And there they will doubtless stay until the hour to meet their comrade."

He flashed a pocket torch on his watch. "We are in good time," he said. "We shall get there well before them. Then we shall have to hide and see what happens."

Straight up the Sound drove the rushing racer, plunging through the rolling swells, tossing the spray to right and left. Ahead of it glowed and winked the fiery eyes of the lighthouses. Along either shore shone innumerable street lamps and the lights of late retiring householders. Save for themselves the water seemed deserted. The great steamers that ply between New England and the metropolis had long since passed and vanished in the misty darkness to the north. No freighters were breasting the waves, no tugs were puffing along with strings of barges in their rear. No ferry-boats were crossing. And none of the legion of sailing craft and motor-boats, none of the thousands of pleasure yachts that sometimes dot the smiling waters in the daytime, was abroad. The little secret-service boat seemed to be alone in that vast expanse of water.

Suddenly the boat careened violently. The boys were alarmed, but their comrades merely smiled.

"We're turning," explained the man at the wheel. "Now we'll go straight into the harbor. And it will be just as well if we make less noise."

He slowed down his engine and the roaring sound died away. The boat fell off in speed, but still pushed ahead with good momentum. For perhaps a mile the boat advanced. Then the driver shut off his engine entirely.

"Those fellows might be in Echo Bay itself," he said. "They couldn't find a safer place to hide than right among the pleasure craft. We won't take any chance of being discovered. We'll just glide in like a shadow and anchor where we can watch things."

He switched over to his electric drive and the boat began to forge ahead again, but with all the stealth of a tiger in the jungle. The operation of its machinery was noiseless, and only the gentle slap of the waves against the bow gave audible evidence of its passage. For a considerable time they rode in silence. In the thick darkness the shore was almost invisible while the glowing street lights that shone here and there served only to accentuate the blackness of the night. Close together in the cockpit huddled the passengers, for the air was raw and chilly.

"Until we've got those fellows safe in handcuffs," said the man in charge of the party, "I don't want one of you to speak aloud. And stay down in the bottom of the boat where you can't be seen."

Noticeably the speed of the little craft fell off, It no longer drove through the waves, but slipped through them so softly that even the gentle splashing at the bow was ended. Presently Henry missed the slight vibration, of which he had been but semi-conscious, and he knew that the pilot had shut off his power completely.

Now the shores, with their towering trees, began to loom up uncertainly in the darkness, and Henry knew that the boat was slipping into the harbor. Presently he became aware of a dark spot ahead of them on the water, then another, and another; and straining his eyes, he saw that before them lay a great company of motor-boats and sailing yachts. Very slowly his own craft drew nearer, for it had all but lost its headway, until it was close to the fleet of pleasure boats. Then there was a tiny splash and one of the secret service men began to pay out the anchor rope over the side. The little boat came to rest, and lay quiet, rolling gently, while its occupants crouched in the cockpit, listening and peering through the thick darkness as they waited.

Never had either of the boys been in such a situation before, and the strangeness, the mysteriousness of it impressed them powerfully. All the sights and sounds of the day were missing and in their place arose a host of unfamiliar sensations. Mist was rising all about them, making the darkness denser and more impenetrable. Not a star was to be seen. The shore-line was only a vague, uncertain black bulk. As they huddled silently in the bottom of the little boat, they became conscious of the voices of the night; but these voices were different from the nocturnal whisperings of field and forest which they knew so well. Now they heard only the lisping of water. Little wavelets broke gently against their slender craft. And all about them rose the musical whisper, the liquid murmur of waters gently lapping the rocks or swelling against the sides of boats. At times the breeze could be heard sighing softly through the rigging of near-by yachts. It was weird and uncanny.

And the sensations that came of it were strange and powerful. In the forest the young scouts had lain in wait for enemies, had hidden in the darkness to trap desperate foes, had watched, with bated breath and pounding hearts, for shadowy forms to appear. They were not unaccustomed to danger and the suspense of an ambush. But in the forest they had solid ground beneath their feet. Trees and other tangible objects were all about them. But here everything seemed unreal, almost ghostly. The darkness of the forest was no blacker than the night here in the open. And yet there was no shady covering of leaves to shut out the light—only a strange, weird, unearthly canopy of mist. In the forest innumerable tree trunks offered concealment to approaching enemies; yet here in the open with nothing tangible to obstruct the vision, it was almost impossible to see anything, strain the eyes as one might.

A feeling of awe came over the young scouts, and both were conscious of a creepy sensation. So unreal appeared their surroundings that it seemed as though anything coming out of the mist would be kin to it, unreal and ghostly. So they sat in the bottom of the boat, only the tops of their heads showing above the low gunwale, as they waited in breathless silence, peering through the night, listening with cocked ear, and straining forward to catch every slightest sound.

Under the covered bow of the boat, the driver flashed his torch for a second on the face of his watch.

"Eleven forty-five," he muttered. "There ought to be something doing soon."

A minute passed. The silence was unbroken. Another minute went by. The sighing of the wind in near-by riggings was the only audible sound. Again a minute passed. No sound of boat or boatmen broke the gloomy silence. Once more the pilot peeped stealthily at his watch and gave a muttered exclamation. A feeling of uneasiness took possession of the watchers. They stirred nervously. Dark fears crept into their minds. Had something happened to alter the plans of the spies? Had Sanders sent another wireless message to his comrades, naming another meeting-place? Henry's heart almost stopped beating at the thought that it might well have happened. Bending toward his comrade, he whispered his fears. His voice trembled as he spoke. Roy uttered a low exclamation of dismay. Then there was silence again, and the four sat listening with strained attention—listening for what they feared they would never hear.

And then they heard it. From far down the Sound came the reports of a rapidly beating marine motor. At first the noise was so faint as scarcely to be audible, like the dropping of a pin on a bare floor. Then the fog seemed to magnify the sound and it became suddenly louder. Then it died away again, but it was more distinct than it had been at first. A minute passed. Noticeably the sound grew in volume. Another minute passed. Distinct now was every beat of the motor. With lips parted, heads slightly turned, and eyes peering through the dark, the watchers waited with beating pulses as the sound came on. There could be no doubt it was made by a fast craft. And there could be no doubt that the boat was rushing northward close to the shore. Was it the boat they waited for? Would it turn at the harbor entrance? Or would it go tearing onward, leaving them in despair?

Now it was almost abreast of the harbor's mouth. Another minute, a few seconds, would tell the story. And not one of the watchers breathed as they hung on the sound. On and on it came, until the scouts knew that it was directly abreast of the channel. Would it turn? Would it enter the harbor? Or would it rush straight by? Unable longer to control himself, Roy stretched out his hand and gripped Henry's shoulder. And Henry, like himself, was all atremble. The secret service men stirred nervously. But nobody said a word.

Then the passage of the sound seemed to end. It was no longer rushing by. It seemed stationary. But momentarily it grew in volume. It was coming straight toward the watchers. The boat had entered the harbor. A sigh of relief escaped every lip.

"Up with your anchor," whispered the pilot, "before he shuts off his power."

His companion leaned stealthily over the side and rapidly paid in the rope, lifting the light anchor over the gunwale and cautiously stowing it in the bottom. And he was none too soon. Hardly was the anchor aboard before the roaring sound ceased and the oncoming boat approached with lessened speed. But the scouts' boat rode free, ready for instant work.

"Down with you," whispered the pilot. "Keep your heads below the gunwale till they're past."

The party crouched lower. On came the spy boat. Its muffled engine beats were hardly louder than the pounding of the hearts that watched. It drove steadily forward. Now it was a few fathoms astern. Now it was abreast. Now it had passed. Stealthily four heads slipped above the gunwale of the scout boat. The spy craft was already lost in darkness. The pilot grasped his wheel. He turned a switch and the boat began to vibrate silently. Then it moved forward, gathering momentum with every second. Under the covered deck the other agent flashed a light on his watch.

"Eleven fifty-eight," he whispered. "They figured it down close."

On went the boat. The craft ahead of them was still invisible though but a few hundred feet distant. But by peering sharply at the water, the pilot could see where it had passed. The surface was still agitated. Faintly came the sound of the muffled motor. The pilot increased his speed, but no sound came from his boat. Like a ghost it glided through the dark waters.

"Look sharp," whispered the pilot. "Let me know if you see them. We've got to get as close to them as we can, and yet we must not be seen."

On went the spy craft. It slid past the park. The street leading to that was faintly illumined by occasional lights.

The pilot uttered a low exclamation of alarm. "If they look back," he whispered, "those lights will betray us. We're right between them and the spies."

Sharply he swung his craft to the right, crowding close to the shallow waters that edged the channel. If he ran into the mud flats disaster might result. But to stay where they would be silhouetted against the street lights was to court discovery. He had chosen the lesser of two evils.

On they went. Not yet had they come in sight of the fugitive craft in front of them. The pilot increased his speed, leaning anxiously forward as he peered through the darkness. Over the sides of the boat his fellows craned their necks, searching the blackness for a glimpse of the quarry.

Suddenly they became aware that the motor ahead of them had stopped. Then masses of shadow seemed to close in on either hand, making the water itself darker than ever. The boat ahead had turned off its power and was propelled only by the momentum it had gained. Instinctively Roy laid his hand on the pilot's shoulder. But the latter had already stopped his engine.

As silent as a shadow the boat slid forward. Suddenly Roy detected what he was looking for. At the same moment a high bank loomed up directly before them. The craft ahead turned toward the right and slipped along the narrowing channel. A few yards further on, it came to rest, its nose lying softly against the muddy shore. Before it the steep bank led upward to an open, level space that both Roy and Henry felt instinctively was a public highway; for on either hand, though at many rods' distance, could be seen the glow of a lamp that was invisible itself.

The scout boat also came to rest, its momentum overcome by the resistance of the water. Like a shadow it lay, not more than fifty yards from the waiting spy craft. Crouching low behind the gunwale, its four occupants held their breath as they watched the party in the boat ahead. Assisted by the faint glow of the distant street lamps, they could vaguely make out the forms of their quarry; while the darkness of their own background rendered them practically invisible.

But no one in the spy boat was looking behind him. All were straining their eyes for the man they had come to meet. Excepting for the gentle voices of the night there was not a sound. Then a whistle rose from the spy boat—a short, sharp note thrice repeated. From the darkness an answer sounded a dozen rods distant. Then footsteps were heard, as some one picked his way uncertainly along the sloping bank. Suddenly the footsteps ceased and stillness reigned. Roy instantly comprehended the fact that the person approaching had paused to listen. His heart gave a leap of joy. He himself had heard no alarming noises, but he instantly guessed that something had caught the ear of the stranger. And Roy knew that his companions who had come by motor-car must have made these sounds. Trembling with excitement, he gripped Henry's shoulder.

On came the man. Now the scouts could vaguely distinguish his form. He called in a low voice, and some one in the spy boat answered. Suddenly the man turned sharp about. From the darkness behind him came the unmistakable sound of a pebble kicked by a human foot. In the opposite direction a stone rolled down the bank and splashed noisily into the water. With an oath, the man on the bank turned and ran toward the motor-boat. To right and left in the darkness came the scurrying of feet and the command "Halt!" The fugitive leaped forward. Frantically the men in the spy craft were trying to head their boat about. The fugitive reached it and leaped aboard. Then he turned to face the figures rushing toward him. At the same instant the scout boat suddenly moved forward. From the spy boat a pistol-shot rang out. Before another could follow, an electric torch was shining full on the spy craft, and the agent in the scout boat was covering the fugitives with his automatic.

"Drop that gun!" he commanded. "Hands up, or I'll fire!"

Taken by surprise, the man who had just boarded the craft let his weapon clatter to the floor. And in the sudden illumination Henry saw with exultation that the man was the motor-car driver, the German agent, Sanders.

"Hands up!" repeated the secret service man imperatively, noticing that one of the fugitives was crouching in the bottom of the boat with his hands hidden. In reply the man straightened up. Like a flash his arm shot out and a pistol cracked. But before a second bullet could follow, a form leaped into the shallow water and a great fist shot into the man's stomach, doubling him up like a jack-knife. The same hand then grasped the nose of the spy craft and dragged it toward the shore, while the pilot of the scout boat brought his craft close beside that of the spies. Other torches flashed in the darkness, and one by one the fugitives were manacled—Sanders, and the spy from the cliff, and the German grocer, and his errand boy, and a stranger who ran the boat.



CHAPTER XXII

A TASK ACCOMPLISHED

Two hours later the party was grouped around Chief Flynn, who had remained in his office to learn the result of the raid. Both motor-boats had been left in charge of the New Rochelle road-house keeper, and the entire party had returned to New York in the two motor-cars—the secret service motor and Sanders' car, for Sanders had left it at the road-house and slipped away into the darkness at midnight. The clerk from Hoboken was under arrest, too. He had been taken up by the man who was watching him. Sanders had eluded his shadow by leaving his car late in the afternoon, at a garage, ostensibly to have it washed, and by later leaving his house surreptitiously in the dark. He had not been able to reach the Balaklavan rendezvous in time to join his companions. But they had a wireless equipment aboard their boat and he had made a later appointment with them. And, even as Captain Hardy had suspected, he had been nosing around Fort Slocum in the darkness.

But this was all the secret service ever learned as to the operations of this gang of wireless spies. The prisoners refused to name those higher up, and the Chief could only guess whose might be the master minds behind the plot.

As for the various wireless agents who were relaying the spy messages to Mexico, several were caught by decoy messages and shared the fate of Sanders and the others.

Even the mystery of the sudden flight of Sanders and his crew was cleared up. Following the Chief's orders, his men on the border had taken the three silver coins away from the Mexican. And, sure enough, the coins contained messages. One was the message from New York concerning the sailing of transports. The other messages were about army secrets, and it is not yet known where they came from or how they got into the hands of the Mexican.

The latter protested violently when asked for his silver dollars, and they had to be taken from him by force. The next day one of his guards discovered that the left cuff of his shirt was missing. The shirt had been intact when he was arrested. No trace of the cuff could be found anywhere. The window of the room where the Mexican was confined overlooked a public street. And it was believed by the secret service men that the spy had written a message on his cuff in some way and dropped it out of the window to a confederate. Thereupon a warning had been flashed back along the wireless line—a warning message in the new cipher that had so puzzled the lads of the wireless patrol.

"It's all clear enough now," sighed Willie, when the story had been put together, "but when you have only one piece of a jig-saw puzzle you can't make much out of it. And one piece was about all we had for a long time. I see it all now, but there's one thing I don't yet understand. Why didn't they use a more difficult cipher?"

"I suppose," explained the Chief, "that this very pursuit and capture of the spies answers that question. They knew that if the secret service picked up their messages, we could sooner or later decipher anything they sent. But even a very simple cipher might baffle one unaccustomed to such things. Always there was the danger that some one would pick up their messages. So they chose ciphers that would bother the ordinary man but that they themselves could read readily. They didn't dare use a cipher that would require a long time to unravel, because they foresaw that they might have to flee on short notice, just as it happened."

"I see," said Willie.

"And now," said the Chief, "I want to tell you boys and your good leader here how much you have done for me and your country. I didn't have faith in your accomplishing much, but I thought that you might be able to pick up wireless messages, if any were abroad, and so I agreed to take you. You see we were almost desperate over the situation. We knew what was going on, but we were so terribly short handed that we could not spare men to run the spies down. I think that we shall have no more trouble. The system is broken up. If we do have trouble, I'm going to send for you boys at once. Meantime, you can now go back home, knowing that few boys have done as much for America and Freedom as you. I am more grateful to you than I can tell you."

The little wireless patrol passed out into the night, its labors ended. Now that the excitement was past, the boys realized how tired and sleepy they were. As they crossed the Bay to their temporary home on Staten Island, they had their last view of the harbor. Now it was almost silent. Only a few boats were ploughing through its waters. The great office-buildings were dark. The fiery lights of the city were extinguished. But bright above the Bay flamed the torch of Liberty. There, in that flickering light, was symbolized the thing that millions of men were giving their lives to protect—the greatest heritage of the ages. And as the boys from Central City looked at the symbolic illumination, their hearts beat exultantly and their eyes grew dim with joy at the thought that they, too, had been able, through months of self-denial and rigid self-discipline, to prepare themselves for the task that was now so happily ended.

THE END