Twining came down with six men, leaving the others to guard the exits from the house and garden.  At the door of the sitting-room he stopped at the head of those he was bringing.  At his feet yawned a gulf in which steps appeared.  The whole of the centre of the floor had disappeared into the wall opposite to the fireplace, and the rough steps led down into a kind of passage that ran in the direction of the unfinished house.  “This is the entrance,” said Jennings, “it works from a concealed button on the wall.  Electricity is used.  You see why the sides of the floor are left bare; the carpet has quite disappeared.  But we have no time to lose,” he jumped down lightly.  “Come along men, hurry up.”

“As we will be at a disadvantage, we may as well get our barkers out,” said the inspector, and the men produced revolvers.  Then they went into the burrow at the tail of the intrepid Jennings.

That gentleman stole along the narrow passage:  It ran straightly for a few yards and then took a turn to the right.  The ground continued to slope for some distance until it terminated in a heavy door of wood.  Jennings fancied this might be locked, and felt a pang of disappointment.  But it proved to be merely closed to.  Apparently the coiners were so sure of their safety that they did not trouble to keep the door locked.  The detective opened it gently, and with the men close at his heels stole forward.  He held his revolver lightly in his right hand, ready for emergencies.  The passage was quite dark, but being narrow, the men had no hesitation in going forward.  Some way down, after leaving the door, the passage branched into two ways, for Jennings came against a wall directly ahead.  Wondering what this meant, he struck a match, and the blue light revealed one passage running down to the left and another opening up to the right.  While the detective hesitated which to take, the darkness was suddenly illuminated with the glare of lamps.  From a dozen electric lights at the sides of the passage sprang a white glow.  At the further end of the sloping passage appeared the figure of a man.  He gave a shout when the figures of the police were revealed in the sudden illumination and vanished suddenly.  There was not a moment to be lost.  Jennings, crying to his men, dashed ahead.  As he neared the end of the burrow, for it was nothing else, a pistol shot rang out and he felt as though his shoulder had been pierced with a red-hot iron.  But the wound did not stop him.

“Quick, men—­quick!  Some stop and guard the double way.  They will try and escape that way.”