"Hum, yes; but overstaying leave isn't such a very serious matter, and think of the reward that's ahead in store for us. Only this cruise, and----" "Hush!" broke in the one addressed as Carl, with an angry intonation; "you must be a fool to talk like that in front of the kid," he went on in a low undertone. "Pshaw!" snarled the other in the same low voice, however. "He's just a country Reuben, with the hayseed still in his hair and the smell of the hog-pen on him--like that one we gambled with in New York--Hank Harkins--wasn't that his name?--on the old 'Idy'." "Just the same, it's well to be prudent," counseled the other, and fell once more to his pacing of the cell. As for Herc, to whom all this, including the reference to Hank, had been, as Carl had guessed, so much Greek, he laid down at full length on the bench. As he had not had more than a few winks of sleep during his seasick night, he soon dropped off into peaceful slumber, despite his uncomfortable couch and serious position. How long he slept, he did not know, but he woke with a start, and was about to open his eyes, when he suddenly closed them again and feigned deep slumber. He had heard something being discussed by the two men with whom he shared the cell that set his pulse to stirring and his heart to beating a wild tattoo. The boy realized that the safety of one of the United States' greatest naval secrets lay, for the time being, in his hands. CHAPTER XIV. A PLOT OVERHEARD. "Say, didn't that boy move?"--the prisoner that Herc knew as Carl put the question. The lad heard rapid footsteps pace across the narrow cell, and felt the hot breath of one of the men in his ear as he lay still and feigned slumber as best he could, although his heart beat so wildly he was sure its agitation must have been audible to the two men. Apparently, however, his ruse succeeded. The men were satisfied that he was wrapped in slumber, for, with a growl, the one that had bent over him said: "He's off; sound as a top." "A good thing," rejoined the other, "both for us and for him." It was Carl who spoke, and the tone in which his soft, refined voice uttered the words left the Dreadnought Boy no room to doubt that if the two plotters had imagined he had overheard them they would have done something exceedingly unpleasant to prevent their secret being betrayed. As it was, however, they seemed to feel no uneasiness and resumed their conversation. "The yacht will be waiting at Boco del Toros, about ten miles above Guantanamo Bay," continued the black-browed man. Herc recognized his bearlike growl. "All we have to do when we get the plans is to steal aboard and sail. Her captain will be prepared for us, and will take us on board when we give the signal."