The detectives had finished this examination when, at an hour in the late afternoon, Henry Lennox and Dr. Mannering returned. The authorities had been informed of the death of Septimus May, and desired that no more than the ordinary formalities should be taken, unless their representatives at Chadlands thought otherwise. But they did not. They were now convinced that no communication existed between the Grey Room and the outer world, and they declared their determination to watch in it during the coming night. As a preliminary to this course, however, they examined each piece of furniture and every picture and other object that they had removed from the room. These told them nothing, and presently they restored the chamber in every particular, re-laid and nailed the carpet, and placed each article as it had stood when they arrived. They continued to decline assistance, and made it clear that nobody was to approach the end of the corridor in which they worked. Alive to the danger, but believing that, whatever its quality, four men could hardly be simultaneously destroyed, they prepared for their vigil. Nor did they manifest any fear of what awaited them. Facts, indeed, may be stubborn things, but even facts will not upset the convictions of a lifetime. Not one of the four for an instant imagined that a supernatural explanation of the mystery existed. Their minds were open, and their wits, long trained in problems obscure and difficult, assured them that the problem was capable of solution and within the power of their wits to solve. They apprehended no discovery from the watch to be undertaken; but, at Frith's orders, they set stolidly about it, as a preliminary to the proceedings of the following day. Once proved that the murderous force was powerless against men prepared and armed against it, and the practical inquiry as to these strange deaths would be entered upon. They came with full powers, and designed to search the house without warning on the following morning, and examine all who dwelt in it.