The night was a warm one, and Gimblet felt no need for his coat, though he was a little uneasy lest his white shirt should show up against the dark background if she should chance to look out. Behind him the trees in the wood stirred noisily and untiringly in the wind, and from time to time an owl cried out of the gloom; but no sound from within the castle reached his ears throughout the long hour during which he stood watching while deftly and methodically the young lady in the library went about her business. He wondered if this girl, who stealthily, in the night, by the gleam of a pocket lantern, was engaged in such questionable employment, were unwarrantably ransacking the belongings of her former host, or believed herself to be exercising a daughter's right in going over the papers of a dead parent. The time came when the last paper was examined, the last drawer quietly pushed back into its place; then, with every sign of disappointment, she slowly rose, and taking up her torch made the tour of the room as if debating whether she had not left some corner unexplored. But the library was scantily furnished, apart from the books that lined the walls, and though she drew more than one volume from its place, and thrust a hand into the back of the shelf, it was with a dispirited air. Soon, with a glance at her watch, she abandoned the search, and slowly and hesitatingly moved in the direction of the door and laid her fingers upon the handle. She did not turn it, however, but stood irresolute, her eyes on the floor. After a moment of indecision, the detective saw her mouth compress firmly, and with a quick movement of the head, as if she were shaking herself free from some persistent and troublesome thought, she turned and walked deliberately towards the alcove at the end of the room. "Now," thought Gimblet, "we shall see where the secret door is concealed." Judge of his surprise and excitement, when the girl stopped before the tall case of the lacquered clock and, opening it, stepped inside and drew the door to behind her. For five minutes, with nose pressed to the pane of the window, the detective waited, expecting her to reappear; then an idea struck him, and he clapped his hand against his leg in his exasperation at not having guessed before. He turned immediately, and using the same precautions as before made good his retreat, and returned by way of the drawing-room window to the library. All was silent there, and the empty room displayed no sign of its nocturnal visitors. Gimblet did not hesitate. He went straight to the clock and pulled open the door. The black interior was as empty and bare as when he had previously examined it, but he betrayed neither astonishment nor doubt as to his next action.