If red-headed, freckle-faced Jerry Macklin, star sprinter of Brighton, ever ran in his life he ran that night. Down across the uneven, hill-dotted dumps he tore at a speed that would have put his school records to shame. Three times he fell, but each time on the instant he was up and off again, without even a thought as to whether or not he had injured himself.

And all the time he kept repeating in his mind, "There's a spy out there planning dangerous things for the navy yard and the United States. Joe's in the icy water watching him, and I must get help as fast as I can."

It was good, too, that he did put forth the last ounce of his strength. Sergeant Martin was just passing through the navy yard gate as Jerry arrived, his uniform covered with loose ashes and dirt, and his hands bleeding from stone cuts received in his falls.

To Sergeant Martin, between gasps, Jerry managed to blurt out enough to make the other understand. Within two more minutes Sergeant Martin had imparted the vital information to the captain of the company of marines charged with guarding the navy yard for that particular night. The captain sent two aides scurrying, one to his major, the other to the office of the navy yard commandant.

Twenty marines, fully armed, were hurried aboard a launch that constantly was kept under steam for just such an emergency, and, with Jerry directing, the boat swung out to Joe's aid.

Rapidly as Jerry had traveled the distance between the spot where Slim waited and the navy yard itself, it seemed like ages to Joe, out there in the icy water, a quarter of a mile from shore.

At first the tense excitement of the manhunt had made him unmindful of the low temperature, and he swam with strong, even, silent strokes that sent his lithe body gliding through the current noiselessly; but when he had come within forty feet of the rowboat its lone occupant had turned suddenly, as though scenting danger, and Joe, after waiting for a few seconds to see what might happen, considered the absolute silence an omen of danger and had dived under water, staying there as long as he could, and coming to the surface at an entirely different point from the boat.

After that the cold got to the very heart of him. His muscles grew numb, he felt his strength waning, and he had to bring the whole force of his will to bear to keep from turning back to shore.

But just as Jerry had maintained his courage and strength by keeping constantly in mind Joe's plight, so Joe stuck to his terrible task, suffering the most severe punishment, by an unwavering confidence in Jerry's ability to get assistance in the shortest possible time.

He could see and hear that the man in the boat was working hastily, even laboriously; and every few seconds there was the smothered splash of something heavy being dropped carefully overboard.

And then, at the most inopportune moment, just when Joe was head and shoulders out of the water, not more than twenty feet away from the boat, the searchlight was thrown full upon him.

He dived; but not before the other man saw him. Joe, swimming ten feet under water, and as hard as he could with the current down stream, knew that he had been discovered, for he heard the quick rap-rap of the oars, the sound dying away as the little craft sped toward shore.

When he did come to the surface it was with the certain feeling that the fatal searchlight had been played upon the scene two minutes too early, and just in time to prevent the capture red-handed of a very questionable character, undoubtedly carrying out some plot for an enemy government.

For as distinctly as he could hear the oars thrashing the water toward shore, he could discern the steady but subdued puffing of a steam launch racing up the river.

Joe was now on the point of exhaustion. He was flapping the water desperately, but he was making no progress, and he was having the greatest difficulty keeping himself afloat. He tried to cry out, and this final effort took his last bit of strength.

The steam launch was then perhaps thirty feet away, but Jerry's words, "Right about here," floated to him as from the opposite side of the river. The boat's searchlight that was then suddenly thrown on blinded him; he lost all account of things, and had the vague feeling of sailing across great spaces on fleecy white clouds.

When he regained partial consciousness Sergeant Martin was in the water with him, and trying to raise his body over the side of the launch; then he relapsed again, for what seemed to him hours, but what was actually only about two minutes, and was awakened to his real senses by the shouts of Slim, on shore.

"Slim's got him," Jerry almost shouted. "Hurry, captain, right off this way to the shore. Slim must have him. Listen to Slim's bellow."

And if there wasn't a first-class ruction in progress just upon the spot from which Slim's vocal signals were emanating, then Slim's voice was deceptive, indeed.

As a matter of fact, there was the finest sort of a fracas afoot.

Slim, on shore, had been a silent and anxious witness to the sudden turning on of the navy yard searchlight, and to all that it exposed—the boat, the man at work in it, Joe in the water, and his discovery by the boat's occupant.

And then, as the light was extinguished, and the whole affair was engulfed in darkness, Slim heard the rapid beating of the oars upon the water, and the rower heading toward shore—and Slim.

Unable to see the craft approaching, he traced its course by sound, and when the man stepped ashore Slim was only a few yards away. Discerning a shadow just ahead of him, the youth threw himself at it with his whole weight, only to grunt his pain and disgust as he came into violent contact with the trunk of a dead tree.

The sound, however, startled the enemy into an exclamation which revealed his whereabouts, and a moment later the two were locked together and rolling over the ground, Slim with a desperate grip upon the stranger's throat, and the latter landing blow after blow upon Slim's stomach.

It was during this mÊlÉe that Slim spied the searchlight of the launch and let out his first call. After that most of his "bellows" were involuntary and but punctuated the rapid-fire attack with which the other man was landing his blows just above Slim's waist-line, or where his waist-line should have been.

As the launch headed toward shore, its searchlight trained over the bow, the man of the rowboat resorted to more desperate tactics. With a tremendous jerk he managed to free his throat from Slim's grasp. An instant later he gave the youth's neck a twist which almost broke it. Then he landed a vicious kick which put poor Slim out of business.

Just as the marines from the launch were climbing ashore the fellow sped off into the denseness of the night; and as his footsteps died away all present trace of him was gone. A dozen of them searched for an hour, but without result, and further investigation along that line had to be abandoned until the following day.

Meanwhile, however, all three lads were hurried back to the navy yard for fresh clothing and other repairs; having received which, together with hot coffee from the cook at the barracks mess, they were permitted, at their own earnest solicitation, to return to the scene with four marines who were to be stationed along that section of the shore for the balance of the night.

What they saw upon their arrival astounded them. Three additional launches had arrived upon the scene, and the commandant of the navy yard was himself directing matters.

He had in his hand a slight rope that ran down into the water, and close beside it was a hose line attached to an apparatus in the boat. The boys knew at once that a diver was at work down on the river bed.

From the side of another launch anchored parallel with the first, and fifteen feet distant, four husky bluejackets were waiting expectantly to divide their strength on two stout ropes that were being attached to something down in the water. The third launch played its flashlight upon the work, while the fourth steamed about, doing patrol duty.

Even as the boys watched, the commandant gave a signal and the sailors began hauling upward on the two heavy ropes. In a moment an oblong box, about two feet long, a foot wide and of the same depth, came dripping from the water. As it was brought to the boat's side two other men grasped it carefully and placed it in the bottom of the launch. Then the ropes, which were attached to a guide line, were hauled down into the river again.

"What does it mean?" Joe asked of Sergeant Martin, who had changed his clothes and arrived back ahead of them.

"What does it mean?" repeated the big sergeant. "It means that you three young men are due for several credits and early recognition, or I'm much mistaken. The man you discovered has not yet been caught, but he cannot escape for long. And when he is captured it will be a long time before he is free again.

"You lads have frustrated a dangerous plot by an enemy government. The river bottom seems to be paved with those cases. They've taken out a dozen already. One of them was opened, and, just as expected, it proved to be a water-tight container for smokeless powder!

"The government that had those boxes hidden there undoubtedly was scheming to have plenty of ammunition ready for use if it ever managed to land its men on American soil.

"But you boys appeared here just in time to blow up the whole plot. You have been in your first real action in the service of your country, and you have come off with flying colors."