"I don't care what you call it, but I see smoke coming out of the chimney. We'll go up there and get somebody to help us." Moved by a common impulse both boys started in the direction of the strange house. Neither was aware that they were entering upon an experience that was to be as mysterious as it was trying. CHAPTER III A MYSTERIOUS HOUSE The sun was shining brightly as the boys moved across the island in the direction of the place they were seeking. As they stopped occasionally to look back over the waters of the lake, they saw that the waves still were tipped with white and the waters still were rough. "I wish I knew where the other fellows are," said Fred, once more stopping to look out over the waters that now were reflecting the light of the afternoon sun. "They are all right," said John, confidently. "I told you both the _Gadabout_ and the other skiff are around the point." "I know you told me so, but that doesn't make it so," said Fred, still unconvinced by the confident manner of his companion. "Look yonder, will you!" said John abruptly as he pointed toward the house they were seeking. "I'm sure there is somebody in there." "It doesn't look as if it would hold together long enough to let any one stay very long inside," laughed Fred. "We'll find out anyway pretty quick who it is." In a brief time the boys arrived at the rear of the little house, which was not much more than a shanty in its appearance. They found that their surmise that smoke was rising from the chimney was correct. There could be no doubt that some one was within the building. Once more the boys turned and looked anxiously toward the lake, eager to discover if any trace of their missing friends could be seen. The waters already were becoming smoother and the rays of the sun were almost blinding as they were reflected by the shining waters. "What shall we do?" said Fred in a low voice. "Shall we rap?" "Of course we'll rap," retorted John. "You talk as if you didn't know what the customs of civilized countries are." "Is knocking one of them?" inquired Fred demurely. "It certainly is." "Well, then, I guess I don't live in the place you are talking about, for nobody has rapped at our door at home for the last ten years. Not since we have put in electric bells." "It's hard work to keep up with you," said John, not strongly impressed by the attempt of his friend to be facetious. "But we'll knock here anyway." Advancing to the kitchen door, John rapped loudly to proclaim the presence of visitors. A silence followed the summons and when several seconds had elapsed John repeated his knocking. Still no one came to welcome them, and then, glancing behind him at his friend, John demurely raised the latch and opened the door.