“That’s very odd of him,” she declared, her dimples coming and going in a most bewildering fashion.  “I can’t imagine why he should do that.”

“Nor I,—­” retorted Arthur with a smile.  “But he’s human, I suppose.  Only do be careful, Violet.  A man so melancholy will need a deal of cheering.”

He was gone before he had fully finished this daring remark, and Violet, left again with her thoughts, lost her glowing colour but not her preoccupation.  The hand which lay upon the packet already alluded to did not move for many minutes, and when she roused at last to the demands of her employer, it was with a start and a guilty look at the small gold clock ticking out its inexorable reminder.

“He will want an answer the first thing in the morning,” she complained to herself.  And opening the packet, she took out first a letter, and then a mass of typewritten manuscript.

She began with the letter which was as characteristic of the writer as all the others she had had from his hand; as witness: 

You probably remember the Hasbrouck murder,—­or, perhaps, you don’t; it being one of a time previous to your interest in such matters.  But whether you remember it or not, I beg you to read the accompanying summary with due care and attention to business.  When you have well mastered it with all its details, please communicate with me in any manner most convenient to yourself, for I shall have a word to say to you then, which you may be glad to hear, if as you have lately intimated you need to earn but one or two more substantial rewards in order to cry halt to the pursuit for which you have proved yourself so well qualified.

The story, in deference to yourself as a young and much preoccupied woman, has been written in a way to interest.  Though the work of an everyday police detective, you will find in it no lack of mystery or romance; and if at the end you perceive that it runs, as such cases frequently do, up against a perfectly blank wall, you must remember that openings can be made in walls, and that the loosening of one weak stone from its appointed place, sometimes leads to the downfall of all.

So much for the letter.

Laying it aside, with a shrug of her expressive shoulders,
Violet took up the manuscript.

Let us take it up too.  It runs thus: 

On the 17th of July, 19—­, a tragedy of no little interest occurred in one of the residences of the Colonnade in Lafayette Place.

Mr. Hasbrouck, a well known and highly respected citizen, was attacked in his room by an unknown assailant, and shot dead before assistance could reach him.  His murderer escaped, and the problem offered to the police was how to identify this person who, by some happy chance or by the exercise of the most remarkable forethought, had left no traces behind him, or any clue by which he could be followed.

The details of the investigation which ended so unsatisfactorily are here given by the man sent from headquarters at the first alarm.