He had been engaged to be married at the time of his illness, and when he learned what was likely to be its result, had offered to release the young lady from all obligation to him.  But she would not be released, and they were married.  This had taken place some five years previous to Mr. Hasbrouck’s death, three of which had been spent by them in Lafayette Place.

So much for the beautiful woman next door.

There being absolutely no clue to the assailant of Mr. Hasbrouck, I naturally looked forward to the inquest for some evidence upon which to work.  But there seemed to be no underlying facts to this tragedy.  The most careful study into the habits and conduct of the deceased brought nothing to light save his general beneficence and rectitude, nor was there in his history or in that of his wife, any secret or hidden obligation calculated to provoke any such act of revenge as murder.  Mrs. Hasbrouck’s surmise that the intruder was simply a burglar, and that she had rather imagined than heard the words which pointed to the shooting as a deed of vengeance, soon gained general credence.

But though the police worked long and arduously in this new direction their efforts were without fruit and the case bids fair to remain an unsolvable mystery.

That was all.  As Violet dropped the last page from her hand, she recalled a certain phrase in her employer’s letter.  “If at the end you come upon a perfectly blank wall—­” Well, she had come upon this wall.  Did he expect her to make an opening in it?  Or had he already done so himself, and was merely testing her much vaunted discernment.

Piqued by the thought, she carefully reread the manuscript, and when she had again reached its uncompromising end, she gave herself up to a few minutes of concentrated thought, then, taking a sheet of paper from the rack before her, she wrote upon it a single sentence, and folding the sheet, put it in an envelope which she left unaddressed.  This done, she went to bed and slept like the child she really was.

At an early hour the next morning she entered her employer’s office.  Acknowledging with a nod his somewhat ceremonious bow, she handed him the envelope in which she had enclosed that one mysterious sentence.

He took it with a smile, opened it offhand, glanced at what she had written, and flushed a vivid red.

“You are a—­brick,” he was going to say, but changed the last word to one more in keeping with her character and appearance.  “Look here.  I expected this from you and so prepared myself.”  Taking out a similar piece of paper from his own pocket-book, he laid it down beside hers on the desk before him.  It also held a single sentence and, barring a slight difference of expression, the one was the counterpart of the other.  “The one loose stone,” he murmured.

“Seen and noted by both.”

“Why not?” he asked.  Then as she glanced expectantly his way, he earnestly added:  “Together we may be able to do something.  The reward offered by Mrs. Hasbrouck for the detection of the murderer was a very large one.  She is a woman of means.  I have never heard of its being withdrawn.”