“Having left the house, I proceeded to do what Gregson had neglected. I telegraphed to the head of the police at Cleveland, limiting my inquiry to the circumstances connected with the marriage of Enoch Drebber. The answer was conclusive. It told me that Drebber had already applied for the protection of the law against an old rival in love, named Jefferson Hope, and that this same Hope was at present in Europe. I knew now that I held the clue to the mystery in my hand, and all that remained was to secure the murderer.

“I had already determined in my own mind that the man who had walked into the house with Drebber was none other than the man who had driven the cab. The marks in the road showed me that the horse had wandered on in a way which would have been impossible had there been anyone in charge of it. Where, then, could the driver be, unless he were inside the house? Again, it is absurd to suppose that any sane man would carry out a deliberate crime under the very eyes, as it were, of a third person, who was sure to betray him. Lastly, supposing one man wished to dog another through London, what better means could he adopt than to turn cabdriver? All these considerations led me to the irresistible conclusion that Jefferson Hope was to be found among the jarveys of the Metropolis.

“If he had been one, there was no reason to believe that he had ceased to be. On the contrary, from his point of view, any sudden change would be likely to draw attention to himself. He would probably, for a time at least, continue to perform his duties. There was no reason to suppose that he was going under an assumed name. Why should he change his name in a country where no one knew his original one? I therefore organized my street Arab detective corps, and sent them systematically to every cab proprietor in London until they ferreted out the man that I wanted. How well they succeeded, and how quickly I took advantage of it, are still fresh in your recollection. The murder of Stangerson was an incident which was entirely unexpected, but which could hardly in any case have been prevented. Through it, as you know, I came into possession of the pills, the existence of which I had already surmised. You see, the whole thing is a chain of logical sequences without a break or flaw.”

“It is wonderful!” I cried. “Your merits should be publicly recognized. You should publish an account of the case. If you won’t, I will for you.”

“You may do what you like, Doctor,” he answered. “See here!” he continued, handing a paper over to me, “look at this!”

It was the Echo for the day, and the paragraph to which he pointed was devoted to the case in question.