“Jove!” burst from Jack’s lips, “what on earth is this fresh complication?”

He had hardly spoken before there came a crash of glass close to his hand, and something flew whistling by him. At the same instant the searchlight was extinguished, and from seaward, where they had last seen the speeding craft, came a dull “B-o-o-m!”

“Knocked that searchlight into smithereens,” was Tom’s exclamation as old Jupe, with an alarmed cry, came running forward at the sound of the screaming projectile and the splintering glass.

“At any rate,” was Jack’s grim retort, “they’ve shown us their hands. Tom, old chap, this thing is going to be bigger than we thought.”

“You think then——”

“That we are not the only persons interested in the Sea King. If I don’t make a big mistake, that shot was a message from our friend X.Y.Z.”

“It looks like it,” admitted Tom; “oh, if we could only glimpse the Sea King!”

“The rocket cattle from her. I’m sure of it. She must have mistaken the lights of that marine raceabout for our signals.”

“Let’s try an answering rocket,” suggested Tom.

“Won’t do any harm. Jupe, quit shivering like a jellyfish and get the rockets out. Two will be enough. Tom, you rig the tube.”

The firing apparatus, a cylinder of galvanized iron, was speedily rigged in place, and by that time Jupe, whose face was an ashen gray tinge, reappeared with the rockets, two powerful signaling instruments, two feet or more in length.

“All right, Tom, touch them off,” came from Jack, as the younger lad proclaimed that all was ready.

There was the sputter of a match, a burst of yellow flame and then, almost instantly, a roar and a shriek as the first of the signals shot aloft, trailing a long tail of golden fire. At two hundred feet it exploded in a shower of blue stars. Almost simultaneously, it seemed, another cluster of red stars were spattered over the sky.

“Hurray! That’s the Sea King, sure enough!” cried Jack; “see, they’ve answered us. Crowd her as much as you can, Tom, it’s a race for all we’re worth now.”

“I can get a bit more speed, but it means overheating the engines,” warned Tom.

“Never mind that. Put us alongside the Sea King ahead of that other chap, and I don’t care if you blow the engines up,” was the curt rejoinder.

Tom shrugged his shoulders as he went below, but a few seconds later the dial hand of the patent log crept up a notch.

“Fourteen knots!” exclaimed Jack, with a note of satisfaction, “we’ll beat her out yet.”

All at once, from out of the obscurity, a grim possibility materialized. Rushing straight for the Vagrant came a sharp bow, with a wave of white phosphorescent foam curling away from it on each side as it cleaved the swells.

“Great guns! They’re trying to ram us!” gasped out Jack as he sensed the meaning of this new peril.

He seized up the speaking tube and bellowed down to Tom with all the force of his lungs.

“Back! Back her for our lives!”

Round spun the spokes of the wheel fast as a revolving squirrel’s cage. The Vagrant’s forward way was checked, but not wholly. To Jack’s horror it seemed impossible that the other vessel could fail in her evident object of ramming the smaller craft.

Less than a few score of feet separated them now. He could hear the hiss of the other craft’s cutwater as it rushed down on them.

“Golly to goodness, Marse Jack, dey sink us fo’ sho’,” wailed Jupe, dropping to his knees in terror on the bridge.

Jack vouchsafed no reply. But the next instant he felt like giving a shout of joy. The backward revolving propeller of the Vagrant was “biting” the water. The motor craft’s forward impulse was checked. She hesitated, stopped, and slowly her bow began to swing. It was not a second too soon. As the Vagrant swung off, the other craft tore by at a vicious speed, and Jack saw that her bow was shaped like a man-of-war’s “ram.” So closely did she race across the Vagrant’s bow that he could see dim figures on her bridge, and could catch a torrent of maledictions, as those in command of the strange vessel saw that their evident purpose had been frustrated.

At the pace she was going. Jack realized that it would be some moments before she could be put on another tack for a fresh onslaught.

“Ahead! Come ahead!” he shouted down the tube, and the propeller of the Vagrant began to churn in a forward direction once more. The lads’ craft forged forward, crossing the troubled wake of the vindictive stranger.

“Glory be!” breathed old Jupe fervently; “ah could heah de angels’ harps dat time, Marse Jack.”

“I don’t know that I wasn’t in the same mental condition myself,” rejoined Jack, with a nervous laugh. His hands shook and his heart beat thickly. The escape had been narrow enough to unnerve older and more experienced persons than this boyish captain.

“Ahoy!” came a sudden voice out of the darkness ahead, “what craft’s that?”

“The Vagrant!” hailed back Jack, with a glad ring in his tones; “is that the Sky King?”

“Aye! aye! Thank heaven, you’ve come—in time,” was the answering hail from the yacht.

A moment later, against the stars. Jack could trace the spidery outlines of the larger vessel’s spars and wireless aerials and rigging.

“This is Jack Chadwick,” he shouted, not giving a thought to the stranger craft now, but in a torment of anxiety to know what it all portended, “is my father on board?”

There was a pause. Across the water there came a confused murmur of voices, but what they said was not audible.

“Sea King, ahoy!” hailed Jack impatiently, “is my father on board and well?”

“Your father is well, we hope, but he’s not on board,” came back the reply in somewhat hesitating tones.

“Not on board!” stammered Jack, feeling for an instant as if he had been struck a heavy blow, “then where is he?”

“Come alongside. Master Jack,” was the response, “there’s a lot to be told.”

The black hulk of the Sea King was plainly visible now, and Jack, steering carefully, with one hand on the engine-room signaling device, skillfully maneuvered the Vagrant alongside of the bigger craft. As he did so an accommodation ladder was lowered, and several heads appeared along the yacht’s rail.

“Stop her,” chimed the signal.

Then came the order to reverse and then “stop” once more. Jupe, with a line in his hand, leaped for the accommodation ladder. Tom, emerging on deck, took in the situation in a glance and made for the stern. He hurled another line, which was caught from above. In as short a time as it takes to tell it, the Vagrant was snugly moored alongside her larger consort.

Jack, with his head in a whirl, stepped from the bridge. Tom was at his side in an instant.

“Is all well with Uncle Chester?” he demanded impatiently. “Is he on board?”

“No, he isn’t,” came the staggering reply, in a voice that was half a sob. It was a bolt from the blue that had assailed the lad, and who will blame him for being utterly unnerved by the blow fate had just dealt him.

Tom was silent for an instant. Tidings that stun have a way of sinking in slowly. Then, as the two lads stood at the foot of the ladder, he flung his arm around Jack’s shoulder, and from his gritted teeth came speech:

“If harm has come to him. Jack, those who have caused it will have to pay—and pay big!”

And so the two lads ascended the ladder to the Sea King’s deck, followed by the awe-struck Jupe.