“What is it, Frank?” breathed a faint whisper close to his ears; and he became conscious of the fact that Will had also heard the sound, and was listening in his lower berth, his heart doubtless almost standing still with sudden anxiety. For answer Frank slipped gently out of his bed. His outstretched hand came in contact with his gun, simply because he knew just where he had placed the weapon. It was a double-barreled shotgun, a hammerless, that had been given to Frank at his last birthday by his three chums, and which as yet he had not had the pleasure of using much. He knew that Will must have guessed what he was doing, for he caught the intake of breath that signified renewed alarm. Frank, however, did not creep toward the door, and fling it suddenly open, as no doubt his chum anticipated he would do. He had not the slightest idea of shooting at any intruder, his sole intention being to give the other a good scare, that would be apt to make him think twice before returning again to the moored houseboat. There were four windows to the cabin, small affairs, each covered with the heavy wire that is used in stables, and places where, air being needed, it is also advisable to keep out intruders. But Frank happened to know that one of these had been only partly covered in this manner, and that there was plenty of room whereby he could thrust the barrels of his gun out, in order to shoot. This he did without any further delay. The boom of the shotgun sounded loud in the confined space of the houseboat cabin. “Whoop!” yelled Bluff, as he came tumbling down from his elevated berth, doubtless under the impression that an earthquake had dropped in upon them for a visit. Jerry followed suit instantly. Meanwhile, Frank was feeling for his little electric torch, which he had kept within reach of his hand, in case he wanted to see the time during the night, an alarm clock being one of the fixtures of the _Pot Luck_ equipment. “What under the sun happened?” gasped Jerry; and just then Frank snapped on the bright ray of light, when they immediately saw that he was holding his gun in the other hand. “Get some clothes on, fellows!” said Frank, quietly; yet smiling to see the blank expression on the faces of the pair who had been aroused as if by the discharge of a cannon. “What did you shoot, Frank?” demanded Bluff, as, in obedience to the words of one who was looked up to as the leader of the set, he began to draw on a pair of trousers, with the others following suit. “Nothing,” replied Frank. “But say, you didn’t do that just to give us a scare; that wouldn’t be like you, Frank,” ventured Jerry. “If it were Bluff here, I’d think that was the case, because he’s always trying some joke or other. Tell us, Frank, what’s up?” “We heard some wild animal trying to get in here, and Frank shot it through one of the windows!” Will declared, solemnly; for that was just what he believed had happened.