"It's a _door_, just as it looks," explained Sally, "and we never even guessed it was there. I happened to be leaning against that part of the wall as I sawed, balancing myself against it, and sometimes pushing pretty hard. All of a sudden it gave way, and swung out like that, and I almost tumbled in. I was so astonished I hardly knew what had happened!" "But what's behind it?" cried Doris, snatching the candle and hurrying forward to investigate. They peered together into the blackness back of the newly revealed door, the candle held high above their heads. "Why, it's a _tunnel_!" exclaimed Sally. "A great, long tunnel, winding away. I can't even see how far it goes. Did you ever?" The two girls stood looking at each other and at the opening in a maze of incredulous speculation. Suddenly Sally uttered a satisfied cry. "I know! I know, now! We never could think where all the rest of the wood from the _Anne Arundel_ went. It's right here!" It was evidently true. The tunnel had been lined, top and bottom and often at the sides, with the same planking that had lined the cave, and at intervals there were stout posts supporting the roof of it. Well and solidly had it been constructed in that long ago period, else it would never have remained intact so many years. "Doris," said Sally presently, "where do you suppose this leads to?" "I haven't the faintest idea," replied her friend, "except that it probably leads to the treasure or the secret, or whatever it is. That much I'm certain of now." "So am I," agreed Sally, "but, here's the important thing. Are we to go in there and find it?" Doris shrank back an instant. "Oh, I don't know!" she faltered. "I'm not sure whether I dare to--or whether Mother would allow me to--if she knew. It--it _might_ be dangerous. Something might give way and bury us alive." "Well, I'll tell you what I'll do," announced Sally courageously. "I'll take a candle and go in a way by myself and see what it's like. You stay here with Genevieve, and I'll keep calling back to you, so you needn't worry about me." Before Doris could argue the question with her, she had lighted another candle and stepped bravely into the gloom. Doris, at the opening, watched her progress nervously, till a turn in the tunnel hid her from sight. "Oh, Sally, do come back!" she called. "I can't stand this suspense!" "I'm all right!" Sally shouted back. "After that turn it goes on straight for the longest way. I can't see the end. But it's perfectly safe. The planks are as strong as iron yet. There isn't a sign of a cave-in. I'm coming back a moment." She presently reappeared.