Upon the steps of the building, amid the crowd of brokers and speculators, I saw a tall, broad-shouldered man of fifty or fifty-five, his face keen, shrewd and hard, broad at the temples and tapering to a strong jaw, a yellow-gray mustache and imperial half-hiding and half-revealing the firm lines of the mouth, with the mark of the wolf strong upon the whole. It was a face never to be forgotten as long as I should hold memory at all. It was the face I had seen twelve hours before in the lantern flash in the dreadful alley, with the cry of murder ringing in my ears. Then it was lighted by the fierce fires of rage and hatred, and marked with the chagrin of baffled plans. Now it was cool, good-humored, alert for the battle of the Exchange that had already begun. But I knew it for the same, and was near crying aloud that here was a murderer. I clutched my nearest neighbor by the arm, and demanded to know who it was. “Doddridge Knapp,” replied the man civilly. “He's running the Chollar deal now, and if I could only guess which side he's on, I'd make a fortune in the next few days. He's the King of Pine Street.” While I was looking at the King of the Street and listening to my neighbor's tales of his operations, Doddridge Knapp's eyes met mine. To my amazement there was a look of recognition in them. Yet he made no sign, and in a moment was gone. This, then, was the enemy I was to meet! This was the explanation of Detective Coogan's hint that I should be safer in jail than free on the streets to face this man's hatred or revenge. I must have stood in a daze on the busy street, for I was roused by some one shaking my arm with vigor. “Come! are you asleep?” said the man, speaking in my ear. “Can't you hear?” “Yes, yes,” said I, rousing my attention. “The chief wants you.” His voice was low, almost a whisper. “The chief? Who? Where?” I asked. “At the City Hall?” I jumped to the conclusion that it was, of course, the chief of police, on the scent of the murder. “No. Of course not. In the second office, you know.” This was scarcely enlightening. Doubtless, however, it was a summons from my unknown employer. “I'll follow you,” said I promptly. “I don't think I'd better go,” said the messenger dubiously. “He didn't say anything about it, and you know he's rather--” “Well, I order it,” I cut in decisively. “I may need you.” I certainly needed him at that moment if I was to find my way. “Go ahead a few steps,” I said. My tone and manner impressed him, and he went without another word. I sauntered after him with as careless an air as I could assume. My heart was beating fast. I felt that I was close to the mystery and that the next half-hour would determine whether I was to take up Henry Wilton's work or to find my way in safety back to my own name and person. My unconscious guide led the way along Montgomery Street into an office building, up a flight of stairs, and into a back hallway.