of every sort and condition who are in our employ, of the ceaseless yet inoffensive surveillance we maintain.  For example, when your letter came last week I called up the person who has charge of the army list.  There you were, Kenneth Harren, Captain Philippine Scouts, with the date of your graduation from West Point.  Then I called up a certain department devoted to personal detail, and in five minutes I knew your entire history.  I then touched another electric button, and in a minute I had before me the date of your arrival in New York, your present address, and”—­he looked up quizzically at Harren—­“and several items of general information, such as your peculiar use of your camera, and the list of books on Psychical Phenomena and Cryptograms which you have been buying—­”

Harren flushed up.  “Do you mean to say that I have been spied upon, Mr. Keen?”

“No more than anybody else who comes to us as a client.  There was nothing offensive in the surveillance.”  He shrugged his shoulders and made a deprecating gesture.  “Ours is a business, my dear sir, like any other.  We, of course, are obliged to know about people who call on us.  Last week you wrote me, and I immediately set every wheel in motion; in other words, I had you under observation from the day I received your letter to this very moment.”

“You learned much concerning me?” asked Harren quietly.

“Exactly, my dear sir.”

“But,” continued Harren with a touch of malice, “you didn’t learn that my leave is up to-morrow, did you?”

“Yes, I learned that, too.”

“Then why did you give me an appointment for the day after to-morrow?” demanded the young man bluntly.

The Tracer looked him squarely in the eye.  “Your leave is to be extended,” he said.

“What?”

“Exactly.  It has been extended one week.”

“How do you know that?”

“You applied for extension, did you not?”

“Yes,” said Harren, turning red, “but I don’t see how you knew that I—­”

“By cable?”

“Y-yes.”

“There’s a cablegram in your rooms at this very moment,” said the Tracer carelessly.  “You have the extension you desired.  And now, Captain Harren,” with a singularly pleasant smile, “what can I do to help you to a pursuit of that true happiness which is guaranteed for all good citizens under our Constitution?”

Captain Harren crossed his long legs, dropping one knee over the other, and deliberately surveyed his interrogator.

“I really have no right to come to you,” he said slowly.  “Your prospectus distinctly states that Keen & Co. undertake to find live people, and I don’t know whether the person I am seeking is alive or—­or—­”

His steady voice faltered; the Tracer watched him curiously.

“Of course, that is important,” he said.  “If she is dead—­”

“She!”

“Didn’t you say ‘she,’ Captain?”