“Mr. Errington lives abroad now.  He is about to marry.  I don’t think any of his real friends for a moment believed that he committed the dastardly crime.  The police think they know better.  They do know this much, that it could not have been a case of suicide, that if the man who undoubtedly travelled with Mrs. Hazeldene on that fatal afternoon had no crime upon his conscience he would long ago have come forward and thrown what light he could upon the mystery.

“As to who that man was, the police in their blindness have not the faintest doubt.  Under the unshakable belief that Errington is guilty they have spent the last few months in unceasing labour to try and find further and stronger proofs of his guilt.  But they won’t find them, because there are none.  There are no positive proofs against the actual murderer, for he was one of those clever blackguards who think of everything, foresee every eventuality, who know human nature well, and can foretell exactly what evidence will be brought against them, and act accordingly.

“This blackguard from the first kept the figure, the personality, of Frank Errington before his mind.  Frank Errington was the dust which the scoundrel threw metaphorically in the eyes of the police, and you must admit that he succeeded in blinding them—­to the extent even of making them entirely forget the one simple little sentence, overheard by Mr. Andrew Campbell, and which was, of course, the clue to the whole thing—­the only slip the cunning rogue made—­’Au revoir!  Don’t be late to-night.’  Mrs. Hazeldene was going that night to the opera with her husband—­

“You are astonished?” he added with a shrug of the shoulders, “you do not see the tragedy yet, as I have seen it before me all along.  The frivolous young wife, the flirtation with the friend?—­all a blind, all pretence.  I took the trouble which the police should have taken immediately, of finding out something about the finances of the Hazeldene menage.  Money is in nine cases out of ten the keynote to a crime.

“I found that the will of Mary Beatrice Hazeldene had been proved by the husband, her sole executor, the estate being sworn at L15,000.  I found out, moreover, that Mr. Edward Sholto Hazeldene was a poor shipper’s clerk when he married the daughter of a wealthy builder in Kensington—­and then I made note of the fact that the disconsolate widower had allowed his beard to grow since the death of his wife.

“There’s no doubt that he was a clever rogue,” added the strange creature, leaning excitedly over the table, and peering into Polly’s face.  “Do you know how that deadly poison was injected into the poor woman’s system?  By the simplest of all means, one known to every scoundrel in Southern Europe.  A ring—­yes! a ring, which has a tiny hollow needle capable of holding a sufficient quantity of prussic acid to have killed two persons instead of one.  The man in the tweed suit shook hands with his fair companion—­probably