“In which case,” said Wallingford, “it is extremely unlikely that an outsider, without their special opportunities, will be able to solve it. And if he should happen to find a mare’s nest, we shall share the glory and the publicity of his discovery.”

“I don’t think,” said I, “that you need have any anxiety on that score. Dr. Thorndyke is not at all addicted to finding mare’s nests and still less to publicity. If he makes any discovery he will probably keep it to himself until he has the whole case cut and dried. Then he will communicate the facts to the police; and the first news we shall have on the subject will be the announcement that an arrest has been made. And when the police make an arrest on Thorndyke’s information, you can take it that a conviction will follow inevitably.”

“I don’t think I quite understand Dr. Thorndyke’s position,” said Madeline. “What is he? You seem to refer to him as a sort of superior private detective.”

“Thorndyke,” I replied, “is a unique figure in the legal world. He is a barrister and a doctor of medicine. In the one capacity he is probably the greatest criminal lawyer of our time. In the other he is, among other things, the leading authority on poisons and on crimes connected with them; and so far as I know, he has never made a mistake.”

“He must be a very remarkable man,” Wallingford remarked, drily.

“He is,” I replied; and in justification of my statement, I gave a sketch of one or two of the cases in which Thorndyke had cleared up what had seemed to be a completely and helplessly insoluble mystery. They all listened with keen interest and were evidently so far impressed that any doubts as to Thorndyke’s capacity were set at rest. But yet I was conscious, in all three, of a certain distrust and uneasiness. The truth was, as it seemed to me, that none of them had yet recovered from the ordeal of the inquest. In their secret hearts, what they all wanted—even Barbara, as I suspected—was to bury the whole dreadful episode in oblivion. And seeing this, I had not the courage to remind them of their—of our position as the actual suspected parties whose innocence it was Thorndyke’s function to make clear.

In view of my impending departure from London, I stayed until the evening was well advanced, though sensible of a certain impatience to be gone; and when, at length, I took my leave and set forth homeward, I was conscious of the same sense of relief that I had felt on the previous day. Now, for a time, I could dismiss this horror from my mind and let my thoughts occupy themselves with the activities that awaited me at Maidstone; which they did so effectually that by the time I reached my chambers, I felt that I had my case at my fingers’ ends.

I had just set to work making my preparations for the morrow when my glance happened to light on the glazed bookcase in which the long series of my diaries was kept; and then I suddenly bethought me of the abstract which I had promised to make for Thorndyke. There would be no time for that now; and yet, since he had seemed to attach some importance to it, I could not leave my promise unfulfilled. The only thing to be done was to let him have the diary, itself. I was a little reluctant to do this for I had never yet allowed any one to read it. But there seemed to be no alternative; and, after all, Thorndyke was a responsible person; and if the diary did contain a certain amount of confidential matter, there was nothing in it that was really secret or that I need object to any one reading. Accordingly, I took out the current volume, and, dropping it into my pocket, made my way round to King’s Bench Walk.

My knock at the door was answered by Thorndyke, himself, and as I entered the room, I was a little disconcerted at finding a large man seated in an easy chair by the fire with his back to me; and still more so when, on hearing me enter, he rose and turned to confront me. For the stranger was none other than Mr. Superintendent Miller.

His gratification at the meeting seemed to be no greater than mine, though he greeted me quite courteously and even cordially. I had the uncomfortable feeling that I had broken in on a conference and began to make polite preparations for a strategic retreat. But Thorndyke would have none of it.