Then the door of the cabin where Tom Swift and his friends were was suddenly burst open, and seven or eight men threw themselves within. They were led by a man with a small, dark mustache and a little tuft of whiskers on his chin—an imperial. He looked the typical Frenchman, and his words, snapped out, bore out that belief.

What he said was in French, as Tom understood, though he knew little of that language. Also, what the Frenchman said produced an immediate result, for the men following him sprang at our friends with overwhelming fierceness.

Before Tom, Ned, Captain Warner, Mr. Damon or Lieutenant Marbury could grasp any weapon with which to defend themselves, had their intentions been to do so, they were seized.

Against such odds little could be done, though our friends did not give up without a struggle.

"What does this mean?" angrily demanded Tom Swift. "Who are you? What are you doing aboard my craft? Who are—"

His words were lost in smothered tones, for one of his assailants put a heavy cloth over his mouth, and tied it there, gagging him. Another man, with a quick motion, whipped a rope about Tom's hands and feet, and he was soon securely bound.

In like manner the others were treated, and, despite the struggles of Mr. Damon, the two government men and Ned, they were soon put in a position where they could do nothing—helplessly bound, and laid on a bench in the main cabin, staring blankly up at the ceiling. Each one was gagged so effectively that he could not utter more than a faint moan.

Of the riot of thoughts that ran through the heads of each one, I leave you to imagine.

What did it all mean? Where had the strange men come from? What did they mean by thus assaulting Tom and his companions? And what had happened to the others of the crew—Koku, Jerry Mound, the engineer, and George Ventor, the assistant pilot?

These were only a few of the questions Tom asked himself, as he lay there, bound and helpless. Doubtless Mr. Damon and the others were asking themselves similar questions.