“Tell him,” returned von Schalckenberg, “that we have on board a prisoner to be exchanged for Colonel Sziszkinski, who has been unjustly condemned.”

The Russian soldier and sailor conferred together for a moment, and then the latter hailed—

“You have, of course, a proper warrant for this exchange?”

“No,” answered the professor; “we have no warrant beyond our power to enforce our demands. Yet I think this should be sufficient, since we can sink you in an instant if you are foolish enough to prove contumacious. Be good enough, therefore, to bring Colonel Sziszkinski on deck at once, and send him, unhurt, aboard us. In exchange for him we will hand you over a man who calls himself Count Vasilovich.”

The two Russian officers again conferred together for several minutes, frequently directing their glances at the Flying Fish, as though searching her for confirmatory evidence of her power to enforce her crew’s demands; and at length the Russian skipper, facing about, waved his hand and shouted—

“All right; we are willing to make the exchange. One prisoner is as good as another to us, so long as we can show the number contained on our list. We will send the colonel to you forthwith.”

And thereupon he faced about and gave certain orders to his subordinate officer, who in his turn bawled an order to the boatswain to pipe away one of the quarter boats. The soldier, meanwhile, descended from the bridge and went below, doubtless to issue his own orders for the release of the prisoner. A minute later some Russian sailors were seen to go shambling aft aboard the convict-ship and busy themselves upon the task of lowering a boat, which they presently got afloat and took to the Ludwig Gadd’s gangway. And at this point in the proceedings Mildmay shouted through the speaking-tube to Lethbridge that no torpedo-shells would be required; and would he be good enough to bring Vasilovich up on deck, in readiness to hand the fellow over in exchange for the colonel.

Lethbridge proved much more prompt in action than the people on board the convict-ship, and within three minutes of the receipt by him of Mildmay’s communication he stood upon the deck of the Flying Fish, in the company of von Schalckenberg and Vasilovich, awaiting the arrival of the boat by means of which the exchange of prisoners was to be effected.

The amazement of Vasilovich was profound at finding himself afloat in the open sea, with the convict-ship—the name on the bows and stern of which was easily decipherable by him—close alongside. He stared alternately about him and at the steamer that lay gently heaving upon the slight swell within a biscuit-toss of him with an expression of mingled bewilderment and incredulity that proved highly diverting to the two men between whom he stood; and presently, turning to the professor, he gasped—

“Why, Herr Professor, what does this mean? When you last night called upon me I was in my own château at Pargolovo; and when you compelled me to enter this ship—if ship it is—it was stationary on dry land. Now it is afloat, upon the waters of the Black Sea, if I am to believe my eyes! I cannot understand it! What does it mean?”