“After a quarter of an hour spent in obscure hints, Kershaw, finding the cautious German obdurate, decided to let him into the secret plan, which, he averred, would place thousands into their hands.”

Instinctively Polly had put down her paper; the mild stranger, with his nervous air and timid, watery eyes, had a peculiar way of telling his tale, which somehow fascinated her.

“I don’t know,” he resumed, “if you remember the story which the German told to the police, and which was corroborated in every detail by the wife or widow.  Briefly it was this:  Some thirty years previously, Kershaw, then twenty years of age, and a medical student at one of the London hospitals, had a chum named Barker, with whom he roomed, together with another.

“The latter, so it appears, brought home one evening a very considerable sum of money, which he had won on the turf, and the following morning he was found murdered in his bed.  Kershaw, fortunately for himself, was able to prove a conclusive alibi; he had spent the night on duty at the hospital; as for Barker, he had disappeared, that is to say, as far as the police were concerned, but not as far as the watchful eyes of his friend Kershaw were able to spy—­at least, so the latter said.  Barker very cleverly contrived to get away out of the country, and, after sundry vicissitudes, finally settled down at Vladivostok, in Eastern Siberia, where, under the assumed name of Smethurst, he built up an enormous fortune by trading in furs.

“Now, mind you, every one knows Smethurst, the Siberian millionaire.  Kershaw’s story that he had once been called Barker, and had committed a murder thirty years ago, was never proved, was it?  I am merely telling you what Kershaw said to his friend the German and to his wife on that memorable afternoon of December the 10th.

“According to him Smethurst had made one gigantic mistake in his clever career—­he had on four occasions written to his late friend, William Kershaw.  Two of these letters had no bearing on the case, since they were written more than twenty-five years ago, and Kershaw, moreover, had lost them—­so he said—­long ago.  According to him, however, the first of these letters was written when Smethurst, alias Barker, had spent all the money he had obtained from the crime, and found himself destitute in New York.

“Kershaw, then in fairly prosperous circumstances, sent him a L10 note for the sake of old times.  The second, when the tables had turned, and Kershaw had begun to go downhill, Smethurst, as he then already called himself, sent his whilom friend L50.  After that, as Mueller gathered, Kershaw had made sundry demands on Smethurst’s ever-increasing purse, and had accompanied these demands by various threats, which, considering the distant country in which the millionaire lived, were worse than futile.

“But now the climax had come, and Kershaw, after a final moment of hesitation, handed over to his German friend the two last letters purporting to have been written by Smethurst, and which, if you remember, played such an important part in the mysterious story of this extraordinary crime.  I have a copy of both these letters here,” added the man in the corner, as he took out a piece of paper from a very worn-out pocket-book, and, unfolding it very deliberately, he began to read:—­