M. Armand had been gazing at me intently, but now his look relaxed, and I fancied that he drew a deep breath as a man might do when relieved of a burden.  At the back of my brain a vague and shadowy suspicion began to form—­a suspicion that perhaps M. Armand knew more of this affair than he had as yet acknowledged.

“You did not, by any chance, know him?” I asked carelessly.

“No, I think not.  But there is one thing I do not understand, Mr. Lester, and you will pardon me if I am indiscreet.  But I do not understand what this Drouet, as you call him, was doing in the house of Mr. Vantine.”

“He was trying to get possession of the letters,” I said.

“Oh, so it was that!” and my companion nodded.  “And in trying to get those letters, he was killed?”

“Yes, but what none of us understands, M. Armand, is how he was killed.  Who or what killed him?  How was that poison administered?  Can you suggest an explanation?”

He sat for a moment staring thoughtfully out of the window.

“It is a nice problem,” he said, “a most interesting one.  I will think it over, Mr. Lester.  Perhaps I may be able to make a suggestion.  I do not know.  But, in any event, I shall see you again Wednesday.  If it is agreeable to you, we can meet at the house of Mr. Vantine and exchange the cabinets.”

“At what time?”

“I do not know with exactness.  There may be some delay in getting the cabinet from the ship.  Perhaps it would be better if I called for you?”

“Very well,” I assented.

“Permit me to express again my apologies that such a mistake should have been made by us.  Really, we are most careful; but even we sometimes suffer from careless servants.  It desolates me to think that I cannot offer these apologies to Mr. Vantine in person.  Till Wednesday, then, Mr. Lester.”

“Till Wednesday,” I echoed, and watched his erect and perfectly-garbed figure until it vanished through the doorway.  A fascinating man, I told myself as I turned back to my desk, and one whom I should like to know more intimately; a man with a hobby for the mysteries of crime, with which I could fully sympathise; and I smiled as I thought of the burning interest with which he had listened to the story of the double tragedy.  How naively he had confessed his thought that he would have made a great detective—­or a great criminal; and here he was only a dealer in curios.  Well, I had had the same thought, more than once—­and here was I, merely a not-too-successful lawyer.  Decidedly, M. Armand and myself had much in common!

CHAPTER XVIII

I PART WITH THE BOULE CABINET

The coroner’s inquest was held next day, and my surmise proved to be correct.  The police had discovered practically no new evidence; none, certainly, which shed any light on the way in which Drouet and Philip Vantine had met death.  Each of the witnesses told his story much as I have told it here, and it was evident that the jury was bewildered by the seemingly inextricable tangle of circumstances.