“Surely you forget,” I said, “that the whole thing is essentially a matter of the past—­so far as I am concerned?”

“Answer me this,” retorted Mr. Bruff.  “Is the Moonstone at the bottom of all the mischief—­or is it not?”

“It is—­of course.”

“Very good.  What do we believe was done with the Moonstone, when it was taken to London?”

“It was pledged to Mr. Luker.”

“We know that you are not the person who pledged it.  Do we know who did?”

“No.”

“Where do we believe the Moonstone to be now?”

“Deposited in the keeping of Mr. Luker’s bankers.”

“Exactly.  Now observe.  We are already in the month of June.  Towards the end of the month (I can’t be particular to a day) a year will have elapsed from the time when we believe the jewel to have been pledged.  There is a chance—­to say the least—­that the person who pawned it, may be prepared to redeem it when the year’s time has expired.  If he redeems it, Mr. Luker must himself—­according to the terms of his own arrangement—­take the Diamond out of his banker’s hands.  Under these circumstances, I propose setting a watch at the bank, as the present month draws to an end, and discovering who the person is to whom Mr. Luker restores the Moonstone.  Do you see it now?”

I admitted (a little unwillingly) that the idea was a new one, at any rate.

“It’s Mr. Murthwaite’s idea quite as much as mine,” said Mr. Bruff.  “It might have never entered my head, but for a conversation we had together some time since.  If Mr. Murthwaite is right, the Indians are likely to be on the lookout at the bank, towards the end of the month too—­and something serious may come of it.  What comes of it doesn’t matter to you and me except as it may help us to lay our hands on the mysterious Somebody who pawned the Diamond.  That person, you may rely on it, is responsible (I don’t pretend to know how) for the position in which you stand at this moment; and that person alone can set you right in Rachel’s estimation.”

“I can’t deny,” I said, “that the plan you propose meets the difficulty in a way that is very daring, and very ingenious, and very new.  But——­”

“But you have an objection to make?”

“Yes.  My objection is, that your proposal obliges us to wait.”

“Granted.  As I reckon the time, it requires you to wait about a fortnight—­more or less.  Is that so very long?”

“It’s a life-time, Mr. Bruff, in such a situation as mine.  My existence will be simply unendurable to me, unless I do something towards clearing my character at once.”

“Well, well, I understand that.  Have you thought yet of what you can do?”

“I have thought of consulting Sergeant Cuff.”

“He has retired from the police.  It’s useless to expect the Sergeant to help you.”

“I know where to find him; and I can but try.”

“Try,” said Mr. Bruff, after a moment’s consideration.  “The case has assumed such an extraordinary aspect since Sergeant Cuff’s time, that you may revive his interest in the inquiry.  Try, and let me hear the result.  In the meanwhile,” he continued, rising, “if you make no discoveries between this, and the end of the month, am I free to try, on my side, what can be done by keeping a lookout at the bank?”