Harry strolled away after a while.  He did not tell his friends—­nothing was to be gained by telling them—­that he was absolutely sure of the identity of the spy, that it was Shepard.  The question of identity did not matter if they caught him, and his old feeling that it was a duel between Shepard and himself returned.  He believed that the duty to catch the man had been laid upon him.

He began to haunt Richmond at all hours of the night.  More than once he had to give explanations to watchmen about public buildings, but he clung to the task that he had imposed upon himself.  He explained to Dalton and the Virginian found no fault except for Harry’s loss of time that might be devoted to amusement.  Harry sometimes rebuked himself for his own persistency, but Bagby’s taunt had stung a little, and he felt that it applied more to himself than to Dalton.  He knew Shepard and he knew something of his ways.  Moreover, his was the blood of the greatest of all trailers, and it was incumbent upon him to find the spy.  Yet he was trailing in a city and not in a forest.  In spite of everything he clung to his work.

On a later night about one o’clock in the morning he was near the building that housed army headquarters, and he noticed a figure come from some bushes near it.  He instantly stepped back into the shadow and saw a man glance up and down the street, probably to see if it was clear.  It was a night to favor the spy, dark, with heavy clouds and gusts of rain.

The figure, evidently satisfied that no one was watching, walked briskly down the street, and Harry’s heart beat hard against his side.  He knew that it was Shepard, the king of spies, against whom he had matched himself.  He could not mistake, despite the darkness, his figure, his walk and the swing of his powerful shoulders.

His impulse was to cry for help, to shout that the spy was here, but at the first sound of his voice Shepard would at once dart into the shrubbery, and escape through the alleys of Richmond.  No, his old feeling that it was a duel between Shepard and himself was right, and so they must fight it out.

Shepard walked swiftly toward the narrower and more obscure streets, and Harry followed at equal speed.  The night grew darker and the rain, instead of coming in gusts, now fell steadily.  Twice Shepard stopped and looked back.  But on each occasion Harry flattened himself against a plank fence and he did not believe the spy had seen him.

Then Shepard went faster and his pursuer had difficulty in keeping him in view.  He went through an alley, turned into a street, and Harry ran in order not to lose sight of him.

The alley came into the street at a right angle, and, when Harry turned the corner, a heavy, dark figure thrust itself into his path.

“Shepard!” he cried.

“Yes!” said the man, “and I hate to do this, but I must.”

His heavy fist shot out and caught his pursuer on the jaw.  Harry saw stars in constellations, then floated away into blackness, and, when he came out of it, found himself lying on a bed in a small room.  His jaw was bandaged and very sore, but otherwise he felt all right.  A candle was burning on a table near him and an unshuttered window on the other side of the room told him that it was still night and raining.