It was Barton and his crooked accomplices coming back. Fortunately for Rob, they were behind a dune, so that it was impossible for them to observe him. But in a moment, the boy realized with a thrill, they would be upon him. Quick as a flash, and hardly realizing what he was doing, Rob sought the only place of concealment close at hand--the space under the raised bow of the boat. He had hardly squeezed into his cramped quarters before the trio of rascals topped the rise. Rob, with a sinking of the heart, realized at that moment that it would have been better for him to have taken his chances and run away from the scene. But it was too late now. With something that was not exactly fear, but very like it, Rob recognized the fact that he was a concealed passenger, a stowaway, on board a boat on which his presence might cost him his life. As these reflections ran through his mind the men drew closer, talking about the "clever" work they had done. "I guess Barr and his _Peacemaker_ can say good-bye to Uncle Sam now," laughed one of them. "Yes, and the best of it is that Barton will never be suspected," responded the other. "Our government will be manufacturing submarines of the Barr type, while Barr and the United States Government are still in blissful ignorance of the fact that all efforts are for nothing." "You can bet I never put through a job unless I do it right," struck in Barton with great self-complacency. Rob, crouched in his cramped place of concealment, flushed with anger. Right then and there he determined that, come what might, he would see this strange adventure of his through to the bitter end. This resolve was still in his mind when the two men shoved the boat off, bade good-night to the rascally Barton, and, all unconscious of their secreted passenger, got under way. "If I get out of this alive, I'll be lucky," soliloquized Rob as he heard the oars and felt the boat moving through the water. "I wonder if I've done right? At any rate I'm in it now, and, as a Boy Scout, I'm going to see it through." CHAPTER XVIII. THE ISLAND HUT. Rob, in his place of concealment, could hear the two men talking as they rowed. Their conversation related, in the main, to the affairs of the night. Apparently, so far as Rob could gather, the stealing of the plans of the submarine was not yet complete. It appeared that Barton was to remain on the island in his capacity as trusted aide to Mr. Barr, and to gather up all he could of the details of the new submarine, down to the smallest particular. Scarcely daring to breathe, Rob listened with all his might to the conversation of the oarsmen. At the same time the thought was running through his mind that he had acted rashly in taking the step he had. But the boy pluckily made up his mind to stick to his resolution of discovering just what was going on inimical to the plans of the United States Government and Mr. Barr.