“You may think that I read the papers with some attention during my sojourn in France, on the look-out for any chance of laying him by the heels. So long as he was free in London, my life would really not have been worth living. Night and day the shadow would have been over me, and sooner or later his chance must have come. What could I do? I could not shoot him at sight, or I should myself be in the dock. There was no use appealing to a magistrate. They cannot interfere on the strength of what would appear to them to be a wild suspicion. So I could do nothing. But I watched the criminal news, knowing that sooner or later I should get him. Then came the death of this Ronald Adair. My chance had come at last. Knowing what I did, was it not certain that Colonel Moran had done it? He had played cards with the lad, he had followed him home from the club, he had shot him through the open window. There was not a doubt of it. The bullets alone are enough to put his head in a noose. I came over at once. I was seen by the sentinel, who would, I knew, direct the colonel’s attention to my presence. He could not fail to connect my sudden return with his crime, and to be terribly alarmed. I was sure that he would make an attempt to get me out of the way at once, and would bring round his murderous weapon for that purpose. I left him an excellent mark in the window, and, having warned the police that they might be needed - by the way, Watson, you spotted their presence in that doorway with unerring accuracy - I took up what seemed to me to be a judicious post for observation, never dreaming that he would choose the same spot for his attack. Now, my dear Watson, does anything remain for me to explain?”

“Yes,” said I. “You have not made it clear what was Colonel Moran’s motive in murdering the Honourable Ronald Adair?”

“Ah! my dear Watson, there we come into those realms of conjecture, where the most logical mind may be at fault. Each may form his own hypothesis upon the present evidence, and yours is as likely to be correct as mine.”

“You have formed one, then?”

“I think that it is not difficult to explain the facts. It came out in evidence that Colonel Moran and young Adair had, between them, won a considerable amount of money. Now, Moran undoubtedly played foul - of that I have long been aware. I believe that on the day of the murder Adair had discovered that Moran was cheating. Very likely he had spoken to him privately, and had threatened to expose him unless he voluntarily resigned his membership of the club, and promised not to play cards again. It is unlikely that a youngster like Adair would at once make a hideous scandal by exposing a well known man so much older than himself. Probably he acted as I suggest. The exclusion from his clubs would mean ruin to Moran, who lived by his ill-gotten card-gains. He therefore murdered Adair, who at the time was endeavouring to work out how much money he should himself return, since he could not profit by his partner’s foul play. He locked the door lest the ladies should surprise him and insist upon knowing what he was doing with these names and coins. Will it pass?”

“I have no doubt that you have hit upon the truth.”

“It will be verified or disproved at the trial. Meanwhile, come what may, Colonel Moran will trouble us no more. The famous air-gun of Von Herder will embellish the Scotland Yard Museum, and once again Mr. Sherlock Holmes is free to devote his life to examining those interesting little problems which the complex life of London so plentifully presents.”