As Harry looked along this passage-way he came to a huge projecting stone, which seemed as though it had been dislodged in some way. So large was this stone, and so peculiar was its dislocation, that Harry could only think of an earthquake as an adequate cause. It was about eight feet in length by four feet in height, and one end jutted forth, while the other end was sunken in, behind the surface of the wall, in a corresponding manner. At the end where the stone jutted out there was a crevice a few inches in width, which seemed well adapted for a place of concealment, and upon this he at once decided. But to prevent the possibility of discovery it was necessary to thrust the package far in, while at the same time it must be arranged in such a way that it could be drawn forth again. This could be done by means of the string with which it was bound up. This he took off, and tying one end to the package, he thrust it into the crevice as far as he could, quite out of sight, leaving the end of the string hanging out about one inch, in such a way that it was discernible to no one except himself. [Illustration: "He Stooped Forward And Picked It Up."] CHAPTER XVIII. IN WHICH HARRY YIELDS TO AN UNCONTROLLABLE IMPULSE, AND RISKS HIS LIFE IN A DARING ADVENTURE. Harry now felt perfectly secure about the package. It seemed to him to be safely hidden, beyond all possibility of discovery; for who could ever venture into this passage-way? and if any one should, how could that package be seen? Still, as to any one venturing here, he had his doubts. There was that mysterious visit. What did that mean? It was a female figure--a woman; young, too, light, active. Who could it have been? It must have been some one familiar with the castle. He now felt convinced that this figure was no apparition, that it was some living person, that she had come down through this very passage-way, and had entered his room, and touched him and whispered to him. So much was clear. And now before him lay this passageway. He was resolved to explore it as far as possible, so as to unfold the mystery. But who was this visitor?--a woman! Was she friend or foe? If a foe, why had she come? What did she expect, or why had she spoken so gently and roused him so quietly? If a friend, why had she fled so hurriedly, without a sign or word? The more he thought it over, the more he felt convinced that his visitor had made a mistake; that she had come expecting to find some one else, and had been startled at the discovery of her mistake. Perhaps Mrs. Russell had bribed one of the Carlist women to carry a message to her husband. That seemed the most natural way of accounting for it.