“Who knows,” he said to himself, “what may be behind it? This is an old baronial sort of hall, and the greater portion of it was, no doubt, built at a time when the construction of such places as hidden chambers and intricate staircases were, in all buildings of importance, considered a disiderata.” That he should make some discovery behind the portrait, now became an idea that possessed him strongly, although he certainly had no definite grounds for really supposing that he should do so. Perhaps the wish was more father to the thought than he, in the partial state of excitement he was in, really imagined; but so it was. He felt convinced that he should not be satisfied until he had removed that panel from the wall, and seen what was immediately behind it. After the panel containing the picture had been placed where it was, it appeared that pieces of moulding had been inserted all around, which had had the effect of keeping it in its place, and it was a fracture of one of these pieces which had first called Charles Holland’s attention to the probability of the picture having been removed. That he should have to get two, at least, of the pieces of moulding away, before he could hope to remove the picture, was to him quite apparent, and he was considering how he should accomplish such a result, when he was suddenly startled by a knock at his chamber door. Until that sudden demand for admission at his door came, he scarcely knew to what a nervous state he had worked himself up. It was an odd sort of tap—one only—a single tap, as if some one demanded admittance, and wished to awaken his attention with the least possible chance of disturbing any one else. “Come in,” said Charles, for he knew he had not fastened his door; “come in.” There was no reply, but after a moment’s pause, the same sort of low tap came again. Again he cried “come in,” but, whoever it was, seemed determined that the door should be opened for him, and no movement was made from the outside. A third time the tap came, and Charles was very close to the door when he heard it, for with a noiseless step he had approached it intending to open it. The instant this third mysterious demand for admission came, he did open it wide. There was no one there! In an instant he crossed the threshold into the corridor, which ran right and left. A window at one end of it now sent in the moon’s rays, so that it was tolerably light, but he could see no one. Indeed, to look for any one, he felt sure was needless, for he had opened his chamber-door almost simultaneously with the last knock for admission. “It is strange,” he said, as he lingered on the threshold of his room door for some moments; “my imagination could not so completely deceive me. There was most certainly a demand for admission.” Slowly, then, he returned to his room again, and closed the door behind him.