I followed them to the door. There was a taxicab waiting; they got in and went up the Avenue. That type of man ought to have a house somewhere on the Avenue; it was August; the house would be closed; I began to put things together. I was standing there when Walker came up. I hailed him. “Walker,” I said, “you got here a moment too late. You see that taxicab?” He made a little whimsical gesture. “I see everything,” he said, “that the devil puts out to annoy me; what’s in the taxicab?” “There’s a case in it,” I said, “for the District Court of the United States, on the criminal side, or I’m a poor detective.” “All detectives are poor,” said Walker. “If they were rich, they would have a town house, a country place and a string of hunters.” “Well,” I said, “that’s what the old boy in the taxicab has got; and he’s got something else that the United States doesn’t allow him to take across a state line.” Walker looked at me queerly. He put the tip of his finger to his forehead. “Touch of the heat?” “Look here,” I said, “isn’t this sort of thing just as much in your line of duty as trying to prevent the crooked cashier from boring from within? Isn’t the United States by a fairly recent statute, helping virtue to evade the dragon?” Walker’s face wrinkled into a twisted smile. “It’s helping the clever _fille de joie_ to levy a little blackmail on the side.” “Wrong dope, in this instance,” I said. I began to describe to him the incident and the two persons. I described them carefully, minutely, and he listened without a word and without a motion. He stood perfectly still, there in the hot street before Bartoldi’s mammoth shop. But his manner had changed. He had now, I noted from the very impassive aspect of the man, a deep, a profound, a moving interest in this affair. He cursed softly as though he chopped the words with his teeth. “Ten minutes too late!” he said. “Where did they go?” Walker was motionless for a moment, his head down, his eyes narrowed in a profound reflection. I interrupted him with a repetition of his words. “Ten minutes too late!” I said. “You are two minutes too late. The taxicab has hardly disappeared in the traffic yonder.” I pointed up the Avenue. Walker did not look up. “I was thinking of Bartoldi,” he said. “I am ten minutes too late for Bartoldi.” “That’s right,” I said. “Bartoldi could have told you who this man was. He must have known him.” “Oh, no,” said Walker. “Bartoldi didn’t know him.” I was astonished. “Surely Bartoldi knew him,” I said. Walker’s voice became a sort of drawl. “Surely he did not know him. Bartoldi would not have been a party to this man’s criminal adventures.” I laughed. “What does Bartoldi care about criminal adventures? He’s a dealer in jewels.” “He will care about this criminal adventure,” said Walker. Then he looked suddenly at me. “Where do you think they went?”