After he left us, Moore and I walked down to the gate and around the grounds, leaving Oakes to attend to details with Martin. Carpenters were very busy around the dining-room, carrying in boards and implements, and examining the woodwork and the balcony. A few of the masons were about the grounds, engaged on small details, and all seemed to be on good terms with Cook and his wife, and Annie. Mike was busy at one end of the garden, and Maloney was not far off. "This, Stone, is to be a day of events here. But things are being done very quietly, are they not? You would suspect nothing out of the way--far less a hunt for a murderer or the investigation of a mystery, would you?" "No; were I not informed, I should think that Oakes had merely a gang of laborers at work." "He has that; but he has also a body of the best detectives, for the purpose, to be had. Maloney and Mike are puzzling him considerably, Stone; they are very close to one another always, and seem quite intimate." "Yes," I replied. "I have noticed it. They both show a great deal of interest in these alterations. Have you noticed how Maloney is watching O'Brien? He keeps him continually in sight." We had approached the front door of the Mansion as we spoke. Oakes was standing just outside, his eyes likewise upon the two gardeners. Our last remarks were made in his presence, and he entered the conversation with a quiet observation to the effect that Maloney seemed to fear that Mike might not attend to his business, but that Mike _would_, nevertheless. I was obliged to acknowledge that I did not quite understand. "Oh, Mike is a good laborer," he explained; "he needs no such watching," and there seemed to be a peculiar significance in his words. They were stated in a slow, indifferent manner that caused me to look at the speaker, but his face wore the inscrutable expression which I had frequently seen before, and I learned nothing. I knew him well enough by this time, however, to realize that something was taking shape in his thoughts. "Now, let us go inside," said he. "After lunch we will attack the final solution of the manner in which these mysterious assaults were performed. Like all such things, it will be simple enough, I know, and the point remaining to determine will be not _how_ it was done, but _by whom_. "I feel confident that that door in the cellar room leads upward to an interspace which communicates with the dining-room through panels in the walls. The peculiar noise--the swish--that I heard, resembled the sudden sliding of a board, and it was the conviction that the person who assaulted Moore disappeared into the wall which made me run downstairs. I felt sure there would be some explanation of it below."