“The one on the left,” sang Reeves, “is Colonel Steele; I fancy you both must know him, And Mr. Murdoch’s on the right, He plays the ’cello, blow him! Both of them work in London Town, So they’re both of them out this morning; Of that there is no matter of doubt, No possible, probable shadow of doubt, No manner of doubt whatever.” “Good,” said Gordon. “I’ll step the rooms, shall I, while you step the passage? We hardly need the tape-measure yet.” “Better do both, if you won’t mind; then the pace will be the same.” And Carmichael busied himself in wandering round the room looking for cracks till Gordon reappeared. “Well,” he said, “what news?” “The fireplace wall, I fancy,” said Gordon. “From the door of Colonel Steele’s room to the door of this, walking down the passage, it takes twelve strides. Inside his room, I only take five strides to the wall. Inside this room, I take a bit over five strides to the same wall. Therefore there must be a thickness of about a pace and a half between Colonel Steele’s room and Reeves’. Now one comes to think of it, he wouldn’t hear Murdock’s ’cello if there was that thickness the other side.” “A pace and a half? The priests must have been on the thin side. Yes, that would be it: there must be a length of about ten feet from the fireplace to the wall on the side of the fireplace opposite to the window. Somewhere in that ten feet we’ve got to find the spring.” “Good heavens!” said Gordon suddenly, “suppose there’s a sliding panel.” “A man couldn’t get through one of these panels—not even you, Gordon, in your well-known human-cobra act,” said Reeves, who had stopped singing for the moment. “No, but a man might put his arm through it, and take the photograph away, and put another in its place, while the people in the room were closely occupied—arranging their hands at bridge, for example.” “You’ve got it!” said Carmichael. “But why, why?” He and Gordon both went to the spot where the photograph had rested on the cornice two nights before. There was a crack near it, through which it might be possible for a man standing in the dark beyond to keep a watch on the inside of the room, but this crack seemed to hold no further secret. It was Gordon who eventually, fingering the little mouldings on the lower side of the cornice, found one which pushed upwards, acting as a sort of latch. A little tug at the remaining mouldings made the panel turn sideways and disclose a triangular opening of a few inches across, through which Reeves’ vociferous rendering of “Annie Laurie” burst into the stillness of the priests’ hiding-place. Chapter XIII The Man in the Passage “Well,” said Gordon, “what do we do next?” “The first thing,” said Carmichael, “is to shut up this hole again exactly as it was. The next thing is to discuss what we do next. And, Reeves, I think it might be best if you went on playing for a little.”