Sir Walter invited them to dine with him, and they did so. There were present the master of Chadlands, Dr. Mannering--who asked to spend the night there--and Henry Lennox; while Masters and Fred Caunter waited upon them. The detectives heard with interest the result of the post-mortem conducted during the morning, and related incidents in the life of Peter Hardcastle. They were all unfeignedly amazed that a man with such a record--one who had carried his life in his hand on many occasions--should have lost it thus, at noonday and without a sound of warning to his fellow-creatures. Dr. Mannering told how he had watched the medical examination, but not assisted at it. All attempts to galvanize back life failed, as the experts engaged immediately perceived they must upon viewing the corpse; and during the subsequent autopsy, when the dead man's body had been examined by chemist and microscopist, the result was barren of any pathological detail. No indication to explain his death rewarded the search. Not a clue or suspicion existed. He was healthy in every particular, and his destruction remained, so far, inexplicable to science. Hardcastle had died in a syncope, as the other victims; that was all the most learned could declare. Impressed by these facts, the four made ready, and Lennox observed that they neither drank during their meal nor smoked after it. At nine o'clock they began their work of the night, but invited nobody to assist them, and begged that they might not be approached until daylight on the following morning. Dr. Mannering took it upon himself earnestly to beg they would abandon the vigil. Indeed, he argued strongly against it. "Consider, gentlemen," he said, "you are now possibly convinced in your own minds that the source of these horrible things is to be found outside the Grey Room, and not in it. I agree with you, so far. We have reached a pitch where, in my judgment, we are justified in believing that some motiveless malignity is at work. But by going into that room, are you not giving somebody another opportunity to do what has already been done? Evil performed without motive, as you know better than I can tell you, must be the work of a maniac, and there may exist in this house, unsuspected and unguessed, a servant afflicted in this awful way. One has heard of such things." The eldest of his listeners felt unspeakable interest in these remarks, since his own opinion inclined in the same direction. He was, however, none the less chagrined that another should thus voice his secret theory. He did not answer, but his chief replied.