After breakfast Mr. Hardcastle begged for a private interview with the master of Chadlands, and for two hours sat in his study and took him through the case from the beginning.

He put various questions concerning the members of the recent house party, and presently begged that Henry Lennox might join them.

“I should like to hear the account of what passed on the night between him and Captain May,” he said.

Henry joined them, and detailed his experience.  While he talked, Hardcastle appraised him, and perceived that certain nebulous opinions, which had begun to crystallize in his own mind, could have no real foundation.  The detective believed that he was confronted with a common murder, and on hearing Henry’s history, as part of Sir Walter’s story with the rest, perceived that the old lover of Mary Lennox had last seen her husband alive, had drunk with him, and been the first to find him dead.  Might not Henry have found an eastern poison in Mesopotamia?  But his conversation with the young man, and the unconscious revelation of Henry himself, shattered the idea.  Lennox was innocent enough.

For a moment, the information of uncle and nephew exhausted, Hardcastle returned to the matter of the breakfast discussion.

“You will, of course, understand that I am quite satisfied a material and physical explanation exists for this unfortunate event,” he said.  “I need hardly tell you that I am unprepared to entertain any supernatural theory of the business.  I don’t believe myself in ghosts, because in my experience, and it is pretty wide, ghost stories break down badly under anything like skilled and independent examination.  There is a natural reason for what has happened, as there is a natural reason for everything that happens.  We talk of unnatural things happening, but that is a contradiction in terms.  Nothing can happen that is not natural.  What we call Nature embraces every conceivable action or event or possibility.  We may fail to fathom a mystery, and we know that a thousand things happen every day and night that seem beyond the power of our wits to explain; but that is only to say our wits are limited.  I hold, however, that very few things happen which do not yield an explanation, sooner or later, if approached by those best trained to examine them without predisposition or prejudice.  And I earnestly hope that this tragic business will give up its secret.”

“May you prove the correctness of your opinions, Mr. Hardcastle,” answered Sir Walter.  “Would you like to see the Grey Room now?”

“I should; though I tell you frankly it is not in the Grey Room that I shall find what I seek.  It does not particularly interest me, and for this reason.  I do not associate Captain May’s death in any way with the earlier tragedy—­that of the hospital nurse, Mrs. Forrester.  It is a coincidence, in my opinion, and probably, if physiology were a more perfect science than, in my experience