“I had thought of that, but the person who wrote these letters is dead.”

“Dead?” I repeated.

“He was killed in a duel some months ago,” explained Mr. Hornblower, gravely.

“By Monsieur X.?” I asked quickly.

“By Monsieur X.,” said Mr. Hornblower, and sat regarding me, his lips pursed, as an indication, perhaps, that he would say no more.

But there was no necessity that he should.  I knew enough of French law and of French habits of thought to realise that if those letters ever came into possession of Monsieur X., the game would be entirely in his hands.  His wife would be absolutely at his mercy.  And the thought flashed through my mind that perhaps in some way he had learned of the existence of the letters, and was trying desperately to get them.  That thought was enough to swing the balance in his wife’s favour.

“I am sure,” I said, “that Mr. Vantine would instantly have consented to your client opening the drawer and taking out the letters.  And, as his executor, I also consent, for, whoever may own the cabinet, the letters are the property of Madame X. All this providing, of course, that this should prove to be the right cabinet.  But I must warn you, Mr. Hornblower, that I believe two men have already been killed trying to open that drawer,” and I told him, while he sat there staring in profound amazement, of my theory in regard to the death of Philip Vantine and of the unknown Frenchman.  “I am inclined to think,” I concluded, “that Vantine blundered upon the drawer while examining the cabinet; but there is no doubt that the other man knew of the drawer, and also, presumably, of its contents.”

“Well!” exclaimed my companion.  “I have listened to many astonishing stories in my life, but never one to equal this.  And you know nothing of this Frenchman?”

“Nothing except that he came from Havre on La Touraine last Thursday, and drove from the dock direct to Vantine’s house.”

“My client also came on La Touraine—­but that, no doubt, was a mere coincidence.”

“That may be,” I agreed, “but it is scarcely a coincidence that both he and your client were after the contents of that drawer.”

“You mean....”

“I mean that the mysterious Frenchman may very possibly have been an emissary of Monsieur X. Madame may have betrayed the secret to him in an unguarded moment.”

Mr. Hornblower rose abruptly.  He was evidently much disturbed.

“You may be right,” he agreed.  “I will communicate with my client at once.  I take it that she has your permission to see the cabinet; and, if it proves to be the right one, that she may open the drawer and remove the letters.”

“If she cares to take the risk,” I assented.

“Very well; I will call you as soon as I have seen her,” he said.  “In any event, I thank you for your courtesy,” and he left the office.

He must have driven straight to her family residence on the Avenue; or perhaps she was awaiting him at his office; at any rate, he called me up inside the half hour.