The inspector pursed his lips, smiled, and shrugged his shoulders.  “Of course we haven’t waited till now to find that out,” he said.

“No, of course.  And, as you say, I didn’t think there is much to be learned from this leather case.  It is almost new, and there isn’t a mark on it.”  And Hewitt handed it back to the inspector.

“Well,” said Plummer, as he returned the case to his pocket, “what’s your opinion?”

“It’s rather an awkward case.”

“Yes, it is.  Between ourselves—­I don’t mind telling you—­I’m having a sharp lookout kept over there”—­Plummer jerked his head in the direction of Mr. Woollett’s chambers—­“because the robbery’s an unusual one.  There’s only two possible motives—­the sale of the cameo or the keeping of it.  The sale’s out of the question, as you know; the thing’s only salable to those who would collar the thief at once, and who wouldn’t have the thing in their places now for anything.  So that it must be taken to keep, and that’s a thing nobody but the maddest of collectors would do, just such persons as—­” and the inspector nodded again toward Mr. Woollett’s quarters.  “Take that with the other circumstances,” he added, “and I think you’ll agree it’s worth while looking a little farther that way.  Of course some of the work—­taking off the lock and so on—­looks rather like a regular burglar, but it’s just possible that any one badly wanting the cameo would like to hire a man who was up to the work.”

“Yes, it’s possible.”

“Do you know anything of Hahn, the agent?” Plummer asked, a moment later.

“No, I don’t.  Have you found him yet?”

“I haven’t yet, but I’m after him.  I’ve found he was at Charing Cross a day or two ago, booking a ticket for the Continent.  That and his failing to turn up to-day seem to make it worth while not to miss him if we can help it.  He isn’t the sort of man that lets a chance of drawing a bit of money go for nothing.”

They returned to the room.  “Well,” said Lord Stanway, “what’s the result of the consultation?  We’ve been waiting here very patiently, while you two clever men have been discussing the matter on the roof.”

On the wall just beneath the trap-door a very dusty old tall hat hung on a peg.  This Hewitt took down and examined very closely, smearing his fingers with the dust from the inside lining.  “Is this one of your valuable and crusted old antiques?” he asked, with a smile, of Mr. Claridge.

“That’s only an old hat that I used to keep here for use in bad weather,” Mr. Claridge said, with some surprise at the question.  “I haven’t touched it for a year or more.”

“Oh, then it couldn’t have been left here by your last night’s visitor,” Hewitt replied, carelessly replacing it on the hook.  “You left here at eight last night, I think?”

“Eight exactly—­or within a minute or two.”

“Just so.  I think I’ll look at the room on the opposite side of the landing, if you’ll let me.”