Sitting there awaiting his return, I tried to ponder the matter reasonably. After all, perhaps the chief was right. Merely because the professor had been absent for a few hours and I had seen what I thought to be his diamond in the laboratory, I had worked myself into a perfect fever of anxiety. I almost smiled to myself. In that businesslike office the whole affair did seem absurd. After all the professor did not have to answer to his servants for his actions. Heavy footsteps, announcing the chief's return, caused me to rise to my feet. A few minutes later, in company with the three officers, I was driving again towards The Grange. * * * * * We made the return journey in almost complete silence. Occasionally the chief would shoot a question at me; but, the night air cooling my fevered brain, my replies were guarded. He realized that fact, for I felt his eyes upon me all the way. What was going on behind that broad forehead, I wondered. Then we reached The Grange. As we mounted the steps, John, his wife herding behind him, flung wide the door. He answered the question in my eyes with a negative shake of his head, and the words, "Nothing fresh, sir." The chief eyed him keenly, then curtly bade him lead the way to the laboratory. John hung back, his face blanched. "I can't, sir," he faltered. The chief turned to me, and, although I wanted to follow John's example, although the atmosphere of the house had again filled me with an unshakable dread, I led the way, standing back at the door to allow the officers to enter first. With calculating gaze the chief slowly took in every detail of the stone apartment. He turned to me. "What is there here to be afraid of?" I pointed hesitatingly towards the crystalline cage. The chief and his men strode across to it. "You don't know how to open this?" the chief shot at me after a brief examination. "No," I replied. "It was not here on my last visit." "When was that?" "Some two or three months ago", I answered. "My work occasions much traveling on my part." * * * * * The chief and his men turned again to the cage, talking in undertones. He turned again to me. "You notice that this thing is built in sections. One of them must be movable. Perhaps--" He paused as his eyes fell upon some wires and tubes that trailed across the floor from underneath the cage to a switchboard fastened to the wall. "Perhaps," he repeated, "it is worked from that board." He crossed over, stared thoughtfully at the shining levers for some seconds, and moved one slightly. The result was astounding. All four of us stared with unbelieving eyes as slowly, without the faintest sound, a section of one wall slid inwards, as if guided by invisible tracks on floor and ceiling.