"Just so--for a purpose," assented Fullaway. "That purpose being, of course, its substitution for the real original article. You did not handle the box which is now upstairs--it is carefully weighted, though it is empty. I believe--nay, I am sure, it contains a sheet of lead under its delicate lining of satin. That, of course, was to deceive Mademoiselle. You heard her say that the jewels were in her box at Christiania, and that she never opened the box until this evening here in Edinburgh? Very good--between here and Christiania somebody substituted the imitation box for the real one. Ah!--in all these great criminal operations there is nothing like sticking to the old, well-worn, tried-and-proved tricks of the trade!--they are like well-oiled, well-practised machinery. And now we come back to the real, great, anxious question--Who did it? And there, Allerdyke, we are at present--only at present, mind!--up against a very big, blank wall." "On the other side of which, my lad, lies the secret of the murder of my cousin," said Allerdyke grimly. "Mind you that! That's what I'm after, Fullaway. Damn all these jewels and things, in comparison with that!--it's that I'm after, I tell you again, and a thousand times again. And I'm considering if I'm doing any good hanging round here after this singing woman when the probable sphere of action lies yonder away at Hull, eh?" "The proper--not probable--sphere of action, my dear sir, is the supper-table to which we're presently going," answered Fullaway, with supreme assurance. "What the singing woman, as you call her, can tell us will most likely make all the difference in the world to our investigations. Remember the shoe-buckle! Have it ready to exhibit when I lead up to it. Then--we shall see." The prima donna, back for her engagement at eleven o'clock, came in flushed and smiling--the extraordinary warmth and fervour of her reception by the audience which she had at first been so inclined to treat with scant courtesy had restored her to good humour, and when she had eaten a few mouthfuls of delicate food and drunk her first glass of champagne she began to laugh almost light-heartedly. "Well, I suppose you've been doing your best, Fullaway," she said, with easy familiarity. "I declare you turned up at the very moment, for that fat Weiss would have been no good. But I'm still wondering how you came to be here, and what this gentleman--Mr. Allerdyke, is it?--is doing here with you. Allerdyke, now--well, that's the same name as that of a man I came across from Christiania with, and left at Hull." Fullaway kicked Allerdyke under the table. "You haven't heard of that Mr. Allerdyke since you left him at Hull, then?" he asked, gazing intently at their hostess. "Heard? How should I hear?" asked the prima donna. "He was just a travelling acquaintance. All the same, I had certainly fixed up to see him in London on a business matter." "You don't read the newspapers, then?" suggested Fullaway.