He did not care to prolong the conversation. He had his work to do, and no words from her or anyone else would deter him from it. As he was quitting the room, he suddenly turned to ask a question. "I beg your pardon, madam. Have you any objection to tell me whether your two servants, Hopley and his wife, occupy the same room and bed?" For a moment or two she gazed at him in silence, possibly in surprise at the question, and then gave her answer almost indifferently. "Not in general, I believe. Hopley's cough is apt to be troublesome at night, and it disturbs his wife. But I really do not know much about their arrangements: they make them without troubling me." The detective proceeded on his mission. He soon discovered the concealed door in the evening sitting-room, and passed into the passage beyond it. Ah, if Salter, or any other criminal, were in hiding within its dark recesses, there would be little chance for him now! The passage, very close and narrow, had no egress on either side; it ended in a flight of nearly perpendicular stairs. Groping his way down, he found himself in a vault, or underground room. Mr. Strange was provided with matches, and lighted one. It was a bare place, the brick walls dripping moisture, the floor paved with stone. Here he discovered another narrow passage that led straight along, it was hard to say how far, and he had need to strike more than one match before he had traversed it. It ended in a flight of stairs: which he ascended, and--found himself in a summer-house at the extreme boundary of the garden. So far the search had not realized his expectations. On the contrary, it was so unsatisfactory as to be puzzling to his experienced mind. There had been no tracks or traces of Philip Salter; no indication that the passages were ever used; and the doors had opened at his touch, unsecured by bolt or bar. Taking a look round him while he strove to solve more than one problem, the detective slowly advanced along the garden. All the garden ground surrounding the house, it must be understood, whether useful or ornamental, was _within_ the circle of the maze of trees. Turning a corner, after passing the fruit trees and vegetables, he came in view of the lawn and of the green-house; also of Ann Hopley, who was plucking some thyme from the herb bed. "Have you found what you were looking for, sir!" she asked, every appearance of animosity gone, as she raised her head to put the question when he came near. "Not yet." "Well, sir, I hope you are satisfied. You may take my word for it that you never will." "Think not?" he carelessly said, looking about him. "Any way, I am not sorry that you have been through them subterranean places underground," she resumed. "My mistress and I have never ventured to look what was in them, and she has not much liked the thought of their being there. We got Hopley to go down one day, but his shoulders stuck in a narrow part, and he had to force 'em back and come up again."