“If only we knew something of the object of Uncle Chester’s mission, we might form a clearer idea of what has happened out here,” ventured Tom. “One thing is certain, the _Sea King_ hasn’t struck a rock——” Jack laughed mirthlessly. “There isn’t a reef or a shoal within a hundred miles of her bearings, as given to us,” he said; “that’s what makes the whole thing such a baffling puzzle. Her boilers and machinery were new. I don’t see what can have happened to them, and surely if the accident had been of that nature, the despatch would have said so. It’s just the vagueness of the whole thing that worries me.” “Complicated by Mister X. Y. Z., whoever he may be,” supplemented Tom. “Do you know, Jack, I’ve got a hunch that we, are destined to see that individual before very long?” A sudden yell from Jupe, who was at the bow keeping a keen lookout according to instructions, cut the night. “Marse Jack! Marse Tom! Look! Look dere, yondah!” There was no need for Jupe to explain himself. Dead ahead, and directly on the _Vagrant’s_ course, a bright streamer of flame slashed the sky like a scimitar of fire. “A rocket!” exploded Jack. As he uttered the exclamation the skyward end of the flaming ribbon burst into a diadem of brilliant scarlet stars. “Here, take the wheel,” choked out Jack, seizing Tom by the shoulder and shoving him into the helmsman’s place. With nimble fingers he unlaced the canvas covering of the _Vagrant’s_ searchlight, snapped the switch on with a tiny sputter of green sparks. and the next instant a pencil of white light was sweeping the darkness ahead. Back and forth it swept and suddenly steadied. As it did so the boys uttered a simultaneous exclamation of amazement. Into the field of light had suddenly swung, not the expected outlines of the _Sea King_, but the form of a low craft without masts or funnels, rushing, at what appeared to be terrific speed, toward the northeast. CHAPTER V—A SHOT IN THE NIGHT “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_!”