“Information!  Child, I have all I want—­all I could desire.”  He laughed, passing his hands over his gray hair.  “We are going to find the girl he is in love with before the week ends!”

“Do you really think so?” she exclaimed.

“Yes.  But you must do a great deal in this case.”

“I?”

“Exactly.”

“And—­and what am I to do?”

“Ride in the Park, child!  And if you see Mr. Gatewood, don’t you dare take your eyes off him for one moment.  Watch him; observe everything he does.  If he should recognize you and speak to you, be as amiable to him as though it were not by my orders.”

“Then—­then I am to be a detective!” she faltered.

The Tracer did not appear to hear her.  He took up the notes, turned to the telephone, and began to send out a general alarm, reading the description of the person whom Gatewood had described.  The vast, intricate and delicate machinery under his control was being set in motion all over the Union.

“Not that I expect to find her outside the borough of Manhattan,” he said, smiling, as he hung up the receiver and turned to her; “but it’s as well to know how many types of that species exist in this Republic, and who they are—­in case any other young man comes here raving of brown eyes and ‘gleams’ in the hair.”

Miss Southerland, to her own intense consternation, blushed.

“I think you had better order that habit at once,” said the Tracer carelessly.

“Tell me, Mr. Keen,” she asked tremulously, “am I to spy upon Mr. Gatewood?  And report to you? . . .  For I simply cannot bear to do it—­”

“Child, you need report nothing unless you desire to.  And when there is something to report, it will be about the woman I am searching for. Don’t you understand?  I have already located her.  You will find her in the Park.  And when you are sure she is the right one—­and if you care to report it to me—­I shall be ready to listen . . .  I am always ready to listen to you.”

“But—­I warn you, Mr. Keen, that I have perfect faith in the honor of Mr. Gatewood.  I know that I could have nothing unworthy to report.”

“I am sure of it,” said the Tracer of Lost Persons, studying her with eyes that were not quite clear.  “Now, I think you had better order that habit . . .  Your mother sat her saddle perfectly . . .  We rode very often—­my lost playmate and I.”

He turned, hands clasped behind his back, absently pacing the room, backward, forward, there in the spring sunshine.  Nor did he notice her lingering, nor mark her as she stole from the room, brown eyes saddened and thoughtful, wondering, too, that there should be in the world so much room for sorrow.

[Illustration:  “‘I am sure of it,’ said the Tracer of Lost Persons.”]

CHAPTER V

Gatewood, burdened with restlessness and gnawed by curiosity, consumed a week in prowling about the edifice where Keen & Co. carried on an interesting profession.