Such, indeed, was the case. The D-17, sister ship to the D-16, in which Lord Hastings and his two young officers had seen many exciting adventures, as related in "THE BOY ALLIES WITH THE TERROR OF THE SEAS," had left the coast of England the day before, heading straight for the strongly fortified German base; and now she was almost there. Just what object Lord Hastings had in view neither Jack nor Frank knew, for Lord Hastings had not yet taken them fully into his confidence concerning this expedition. Since leaving England he had been busy in his cabin almost continuously poring over papers and maps, but both lads had a pretty shrewd idea that the venture was an important one. Now Frank asked: "And what are we going to do in there, sir?" Lord Hastings smiled. "What would be your idea about that?" "Well," said Frank, "there are several things we might do. First, we might sink a couple of German war vessels. We might try and learn the lay of the land--perhaps I should say the water--or we might try and get ashore and so learn other matters of importance. Have I hit it, sir?" "You have," returned his commander dryly; "you've hit it in more ways than one. In fact, I may say you have guessed shrewdly all through." "Then I can do a little guessing, too," declared Jack. "Well?" said Lord Hastings inquiringly. "Well," said Jack, "we first shall probably make an attempt to get ashore, for there we can learn more than we could reconnoitering beneath the water. That's where we shall try to find our information. And we shall sink a couple of the enemy on our way out. Am I right, sir?" "You are," replied Lord Hastings briefly, and turning on his heel he left the bridge and disappeared in his cabin, only to reappear a few moments later, charts and papers in his hands, announcing: "Mr. Chadwick, you will take the wheel yourself. I'll stand beside you and give my orders. These waters are thickly strewn with mines and we can afford to take no chances." Frank obeyed this command without question and Lord Hastings took his place beside him, first remarking to Jack: "You will relieve the lookout forward, Mr. Templeton, and keep your eyes open. I need not mention the need of prompt action should you perceive danger ahead. Slow down to five knots!" "Very well, sir." Jack saluted, and after giving the command that reduced the speed of the vessel, took himself forward. There, at the extreme bow, he relieved a sailor and took the watch himself. Now the D-17, like her sister ship the D-16, which had been sunk off the Dardanelles--an accident in which all on board escaped as by a miracle--was as unlike other under-water craft as day is from night.