“Oh, no doubt, no doubt at all,” replied Fullaway.  “Mademoiselle is impetuous, impulsive, demonstrative, much given to insisting on her own way, but she’s absolutely honest and truthful, and I’ve no doubt whatever—­none!—­that she’s been robbed.  But—­not here.  She never brought those jewels here.  They were not in that box when she came here.  Mademoiselle, my dear sir, was relieved of those jewels either on the steamer, as she crossed from, Christiania to Hull, or during the few hours she spent at the Hull hotel.  The whole thing—­the robbery from your cousin, the robbery from Mademoiselle de Longarde—­is all the work of a particularly clever and brilliant gang of international thieves; and, by the holy smoke, sir, we’ve got our hands full!  For there isn’t a clue to the identity of the operators, so far, unless the lady with whom we are going to sup can help us to one.”

Allerdyke ruminated over this for a moment or two.  Then, after lighting the cigar which Fullaway had offered him, he shook his head—­in grim affirmation.

“I shouldn’t wonder,” he said.  “Certainly, it seems a big thing.  You’re figuring on its having been a carefully concocted scheme?  No mere chance affair, eh?”

“This sort of thing’s never done by chance,” responded the American.  “This is the work of very clever and accomplished thieves who somehow became aware of two facts.  One, that your cousin was bringing with him to England the jewels of the Princess Nastirsevitch.  The other, that Mademoiselle Zelie de Longarde carried her pearls and diamonds in an innocent-looking rosewood box.  My dear sir! you observed that I examined that box with seeming carelessness—­in reality, I was looking at it with the eye of a trained observer.  I am one of those people who, from having knocked about the world a lot, engaging in a multifarious variety of occupations, have picked up a queer scrap-heap of knowledge, and I will lay you any odds you like that I am absolutely correct in affirming that the box which I just now handed to Maggie, the chambermaid, was newly made by a Russian cabinet-maker within the last four weeks!”

“For a purpose?” suggested Allerdyke.

“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.”