“Walter!” she said, “if ever those two men are at your mercy, and if you are obliged to spare one of them, don’t let it be the Count.”

“I will keep this letter, Marian, to help my memory when the time comes.”

She looked at me attentively as I put the letter away in my pocket-book.

“When the time comes?” she repeated.  “Can you speak of the future as if you were certain of it?—­certain after what you have heard in Mr. Kyrle’s office, after what has happened to you to-day?”

“I don’t count the time from to-day, Marian.  All I have done to-day is to ask another man to act for me.  I count from to-morrow——­”

“Why from to-morrow?”

“Because to-morrow I mean to act for myself.”

“How?”

“I shall go to Blackwater by the first train, and return, I hope, at night.”

“To Blackwater!”

“Yes.  I have had time to think since I left Mr. Kyrle.  His opinion on one point confirms my own.  We must persist to the last in hunting down the date of Laura’s journey.  The one weak point in the conspiracy, and probably the one chance of proving that she is a living woman, centre in the discovery of that date.”

“You mean,” said Marian, “the discovery that Laura did not leave Blackwater Park till after the date of her death on the doctor’s certificate?”

“Certainly.”

“What makes you think it might have been after?  Laura can tell us nothing of the time she was in London.”

“But the owner of the Asylum told you that she was received there on the twenty-seventh of July.  I doubt Count Fosco’s ability to keep her in London, and to keep her insensible to all that was passing around her, more than one night.  In that case, she must have started on the twenty-sixth, and must have come to London one day after the date of her own death on the doctor’s certificate.  If we can prove that date, we prove our case against Sir Percival and the Count.”

“Yes, yes—­I see!  But how is the proof to be obtained?”

“Mrs. Michelson’s narrative has suggested to me two ways of trying to obtain it.  One of them is to question the doctor, Mr. Dawson, who must know when he resumed his attendance at Blackwater Park after Laura left the house.  The other is to make inquiries at the inn to which Sir Percival drove away by himself at night.  We know that his departure followed Laura’s after the lapse of a few hours, and we may get at the date in that way.  The attempt is at least worth making, and to-morrow I am determined it shall be made.”

“And suppose it fails—­I look at the worst now, Walter; but I will look at the best if disappointments come to try us—­suppose no one can help you at Blackwater?”

“There are two men who can help me, and shall help me in London—­ Sir Percival and the Count.  Innocent people may well forget the date—­but they are guilty, and they know it.  If I fail everywhere else, I mean to force a confession out of one or both of them on my own terms.”