I never remember feeling more intensely chagrined than when I reached our bleak house twenty minutes late for our early dinner to find the doctor had eaten a hurried meal quarter of an hour before the usual hour and rushed out to attend an urgent case.

I asked at once whether he had been told of the pocket book. Yes, it appeared he had. He had seemed very interested, but had immediately ordered his dinner hour to be advanced and then hurried away without putting further questions.

Was his haste a consequence of what he was told, or merely a coincidence? Well, I was resolved to leave that point in doubt no later than his return. I hardly debated at all the question of what to do. The baffling business of groping in the dark, and daily scheming to discover a window, without giving myself away, had gone on long enough. I had found a head at last and I meant to hit it. It might turn out to be the wrong head; still, I felt convinced I could scarcely fail to discover something fresh.

But though I proposed to take a bold course and make a shortcut to the heart of this infernal mystery, I realised perfectly that if the cut actually led me there, it would prove an exceedingly dangerous byway. It was such a gamble that I shrank from summoning my cousin until it had come off, but I wrote out the code telegram we had arranged and put it in my pocket ready for emergencies. Of the doctor’s two servants the younger anyhow was absolutely trustworthy I was convinced, and I meant to send her with the wire to the post office while I kept guard over the prisoner. And then, to ensure there being a prisoner, I saw that all the chambers of my revolver were loaded and put it in my coat pocket ready to my hand.

The afternoon dragged on, the wind still blustering round the house and the hail now and then rattling on the windows; but no Dr. Rendall appeared. Tea time arrived and still no sign of him. I gave him half an hour’s grace and then had my own tea and returned to the smoking-room. The evening by this time had fallen and the curtains were drawn and the lamps lit.

And then at last I heard him enter the front door. I jumped up and, with a dramatic instinct for taking the centre of the stage, placed myself before the fire, but I heard him run upstairs and it was some minutes before the sound of his descending steps reached me. The moment the door opened I was conscious that one of those peculiar changes I had so often noticed had taken place in the man. He smiled at me, but with a curiously furtive eye, and then he shut the door and came forward.

“You have had tea, I hope,” said he.

I wasted no time in preliminaries. Keeping my right hand closed over the revolver in my pocket I held out the pocket book with my left.

“Dr. Rendall,” I said, “you have heard that Bolton’s pocket book has been found. Here it is. Kindly look at that entry.”

The man started perceptibly and stared at me. Speaking in that tone and without my eye glasses I must have made an astonishing contrast to the Thomas Hobhouse he had last seen that morning at breakfast.

“Read that,” I commanded.

He took the pocket book and I watched him closely. I saw his eyebrows rise as he read.

“What’s all this about?” he asked.

“It is Bolton’s last entry in his note book before he was murdered, and it means that O’Brien is either still in this island, or that a confederate of his is playing traitor in his place, and that one of the two has just committed murder. It is quite impossible that you don’t know something of this!”

His blue eyes now had considerably more anger than guilt in them. In fact I was bound to admit that he looked a fine upstanding man, with his grey moustache, high colour, and an air of unmistakable indignation in his face.

“Who the devil are you?” he demanded.

“I may tell you that I am not Thomas Sylvester Hobhouse, and that I have never taken liquor enough in my life to hurt myself. I am here to investigate certain things that have been going on in this island, and I’ll put one question to you straight, Dr. Rendall. You remember being visited by a certain man Merton last August, When you heard him approaching your house why did you pull down your blind?”

That shot went straight home. All the indignation vanished and I saw on the instant I had him at my mercy.

“What⁠—what⁠—has that to do with it?” he stammered.

“Don’t trouble to try and hedge. As a matter of fact I am Merton and I saw the blind go down myself. Since then we have always been on your tracks, Dr. Rendall.”

“I swear that that had nothing to do with treason!”

“You are accused of treason, your relations to O’Brien were very peculiar, and if you can’t explain that blind and this entry and a number of other things, you will be in an extremely nasty position.”

The doctor made no further effort to stand up to me. He sank into a chair while I stood over him, and I knew I was going to hear the truth at last. And yet this sudden collapse, and indeed his whole attitude, were so unexpected that I felt more puzzled than triumphant.

“Mr. Merton,” he said, “for God’s sake don’t give me away and I’ll tell you the whole truth. My cousin Philip can confirm it⁠—or at least part of it. I came up here because⁠—well, I’d married the wrong woman and gone off the rails a bit and Philip settled me here to keep me straight. I had debts too⁠—I have them still, I may tell you frankly. That’s why I took in O’Brien. I wasn’t supposed to keep any liquor in the house⁠—that was one of the conditions. But damn it, I wasn’t born to be a teetotaler, and that’s the plain truth, Mr. Merton. That devil O’Brien found me out and started to blackmail me⁠—”

“Blackmail?” I asked.

“In his own way. He made me give him liquor⁠—and there we were the pair of us! That’s why I pulled down the blind. The decanter and glasses were all out on this table here! And that’s why O’Brien was afraid you might be sent by his relations. That was the one thing he was afraid of⁠—that he might be found out and taken away.”

I bent over him and sniffed.

“You have had a dram now!” I exclaimed.

“And it’s not the first since you’ve been here either. You see I’m perfectly frank with you, Mr. Merton. If you like to give me away to Philip⁠—well be d⁠⸺⁠d, you can if you like. But you’ll surely not? I’ve told you what I’ve told to no one else.”

There rushed into my mind confirmation enough of part at least of the poor devil’s story. His curious moods, his manner as he entered the room this evening, O’Brien’s impish allusions to liquor when I first visited the house, all fell into their places now. Yet utterly as this had exploded my hopes, I think I was more glad than sorry to see the doctor come out of the ordeal with only this kind of stain on his character. He was a likeable man, we had been capital friends⁠—and he was Jean’s cousin.

“I promise you, doctor,” I said, “that I shall repeat no word of this story⁠—except of course in confidence to those who are on the track of this business in Ransay. Only in return you must tell me absolutely frankly if you have seen any grounds for suspecting O’Brien of anything treasonable⁠—anything whatever.”

The doctor shook his head emphatically.

“The only plotting the man was capable of was to get liquor. Otherwise he was just a gas bag. I’ve seen him too often in a state when he’d have given everything away, if there had been anything to give.”

And then I remembered the pocket book.

“But this entry!” I cried. “How do you explain that?”

The doctor looked at it again and his bewilderment was obviously sincere.

“I’m frankly d⁠⸺⁠d if I can make head or tail of it,” he said. “Bolton must have got on the wrong scent; that’s the only thing I can imagine.”

And then, like a sharp smack in the face, Jean’s reading of that entry came back to me. Could she have guessed right after all? It looked uncommonly like it.

“And yet,” I said to myself, “it’s a great thing to have tested the other hypothesis.”

In fact, if one is not built to be easily dispirited, well, it is not easy to dispirit one. I looked at the doctor, and something in my expression seemed to make him smile. When he smiled he looked so pleasant that my conscience smote me. I told myself he certainly deserved some reparation for the ordeal I had put him through.

“Doctor,” I said, “I am devilish thirsty myself after this bout. Let’s each have a whisky and soda!”

It may or may not have been the wisest suggestion to make. I am not an expert in these matters. But anyhow if he enjoyed his drink as much as I enjoyed mine, it was at least a happy idea.

We had lit our pipes with our glasses at our sides, and I was in the midst of giving the doctor some further reparation in the shape of the true tale of my adventures, when I saw him suddenly start and glance guiltily at his tumbler.

“Is that someone in the hall?” he exclaimed.

“Probably the servants,” I suggested.

The next instant the door opened and, without any announcement, in walked my uncle Sir Francis Merton followed by my cousin Commander John Whiteclett.