“But it is by no means a parallel ease,” I argued; “you were under his treatment before, and I have no reason whatever to doubt his skill.  Why should you feel safer in my hands than in his?”

“Well!” he said, with a sneer, “if Olivia were alive, I dare scarcely have trusted you, could I?  But you have nothing to gain by my death, you know; and I have so much faith in you, in your skill, and your honor, and your conscientiousness—­if there be any such qualities in the world—­that I place myself unfalteringly under your professional care.  Shake hands upon it, Martin Dobree.”

In spite of my repugnance, I could not resist taking his offered hand.  His eyes were fastened upon me with something of the fabled fascination of a serpent’s.  I knew instinctively that he would have the power, and use it, of probing every wound he might suspect in me to the quick.  Yet he interested me; and there was something not entirely repellent to me about him.  Above all for Olivia’s sake, should we find her still living, I was anxious to study his character.  It might happen, as it does sometimes, that my honor and straight-forwardness might prove a match for his crafty shrewdness.

“There,” he said, exultantly, “Martin Dobree pledges himself to cure me.—­Carry, you are the witness of it.  If I die, he has been my assassin as surely as if he had plunged a stiletto into me.”

“Nonsense!” I answered; “it is not in my power to heal or destroy.  I simply pledge myself to use every means I know of for your recovery.”

“Which comes to the same thing,” he replied; “for, mark you, I will be the most careful patient you ever had.  There should be no chance for you, even if Olivia were alive.”

Always harping on that one string.  Was it nothing more than a lore of torturing some one that made him reiterate those words?  Or did he wish to drive home more deeply the conviction that she was indeed dead?

“Have you communicated the intelligence of her death to her trustee in Australia?” I asked.

“No; why should I?” he said, “no good would come of it to me.  Why should I trouble myself about it?”

“Nor to your step-sister?” I added.

“To Mrs. Dobree?” he rejoined; “no, it does not signify a straw to her either.  She holds herself aloof from me now, confound her!  You are not on very good terms with her yourself, I believe?”

“The cab was still standing at the door, and I could not leave before it drove away, or I should have made my visit a short one.  Mrs. Foster was glancing through the window from time to time, evidently on the watch to see the visitor depart.  Would she recognize Johanna?  She had stayed some weeks in Guernsey; and Johanna was a fine, stately-looking woman, noticeable among strangers.  I must do something to get her away from her post of observation.

“Mrs. Foster,” I said, and her eyes sparkled at the sound of her name, “I should be exceedingly obliged to you if you will give me another sight of those papers you showed to me the last time I was here.”