Dear sir—­This is to warn you that your daughter Aileen is running around with a man that she shouldn’t, Frank A. Cowperwood, the banker.  If you don’t believe it, watch the house at 931 North Tenth Street.  Then you can see for yourself.

There was neither signature nor mark of any kind to indicate from whence it might have come.  Butler got the impression strongly that it might have been written by some one living in the vicinity of the number indicated.  His intuitions were keen at times.  As a matter of fact, it was written by a girl, a member of St. Timothy’s Church, who did live in the vicinity of the house indicated, and who knew Aileen by sight and was jealous of her airs and her position.  She was a thin, anemic, dissatisfied creature who had the type of brain which can reconcile the gratification of personal spite with a comforting sense of having fulfilled a moral duty.  Her home was some five doors north of the unregistered Cowperwood domicile on the opposite side of the street, and by degrees, in the course of time, she made out, or imagined that she had, the significance of this institution, piecing fact to fancy and fusing all with that keen intuition which is so closely related to fact.  The result was eventually this letter which now spread clear and grim before Butler’s eyes.

The Irish are a philosophic as well as a practical race.  Their first and strongest impulse is to make the best of a bad situation—­to put a better face on evil than it normally wears.  On first reading these lines the intelligence they conveyed sent a peculiar chill over Butler’s sturdy frame.  His jaw instinctively closed, and his gray eyes narrowed.  Could this be true?  If it were not, would the author of the letter say so practically, “If you don’t believe it, watch the house at 931 North Tenth Street”?  Wasn’t that in itself proof positive—­the hard, matter-of-fact realism of it?  And this was the man who had come to him the night before seeking aid—­whom he had done so much to assist.  There forced itself into his naturally slow-moving but rather accurate mind a sense of the distinction and charm of his daughter—­a considerably sharper picture than he had ever had before, and at the same time a keener understanding of the personality of Frank Algernon Cowperwood.  How was it he had failed to detect the real subtlety of this man?  How was it he had never seen any sign of it, if there had been anything between Cowperwood and Aileen?

Parents are frequently inclined, because of a time-flattered sense of security, to take their children for granted.  Nothing ever has happened, so nothing ever will happen.  They see their children every day, and through the eyes of affection; and despite their natural charm and their own strong parental love, the children are apt to become not only commonplaces, but ineffably secure against evil.  Mary is naturally a good girl—­a little wild, but what harm can befall