It was shortly after the noon hour when the saw made its way through the fourth side of the square. In a hush of breathless expectation, they lifted the piece of timber, prepared for--who could tell what wondrous secret beneath it? The space it left was absolutely empty of the slightest suggestion of anything remarkable. It revealed the sandy soil of the embankment into which the cave was dug, and nothing else whatever. The disgusted silence that followed Doris was the first to break. "Of course, something may be buried down here, but I doubt it awfully. I'm sure we would have seen some sign of it, if this had been the right corner. However, give me that trowel, Sally, and we'll dig down a way." She dug for almost a foot into the damp sand, and finally gave it up. "How could any one go on digging down in the space of only twenty-one inches?" she exclaimed in despair. "If one were to dig at all, the space ought to be much larger. No, this very plainly isn't the right corner. Let's go outside and eat our lunch, and then, if we have any courage left, we can come back and begin on another corner. Personally, I feel as if I should scream, if I had to put my hand to that old saw again!" But a hearty luncheon and a half hour of idling in the sunlight above ground after it, served to restore their courage and determination. Sally was positive that the corner diagonally opposite was the one most likely to yield results, and Doris was inclined to agree with her. Genevieve, however, flatly refused to re-enter the cave so they were forced to adopt the scheme of the morning, one remaining always outdoors with her, as they did not dare let her roam around by herself. Sally volunteered to take the first shift at the sawing, and after they had measured off the twenty-one inch square in the opposite corner she set to work, while Doris stayed outside with Genevieve. Seated with a picture-book open on her lap, and with Genevieve cuddled close by her side, she was suddenly startled by a muffled, excited cry from within the cave. Obviously, something had happened. Springing up, she hurried inside, Genevieve trailing after her. She beheld Sally standing in the middle of the cave, candle in hand, dishevelled and excited, pointing to the side of the cave near which she had been working. "Look, look!" she cried. "What did I tell you?" Doris looked, expecting to see something about the floor in the corner to verify their surmises. The sight that met her eyes was as different as possible from that. A part of the wall of the cave, three feet in width and reaching from top to bottom had opened and swung inward like a door on its hinges. "What _is_ it?" she breathed in a tone of real awe.