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.
"_Ex_actly, 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.