That functionary was unable to throw any light on where Retto had gone. Evidently, for the time being, the chase had come to an end. Larry made his way to the nearest elevated station and rode in the direction of the Potter home. He had no definite plan in mind, and, more from a whim than anything else, he decided to walk past the house. He did not expect it, but he had an idea--a very faint one--that he might see Grace. Of course, if he saw her at the window, where she sometimes sat, it would be no more than polite to go in and tell her what the carrier had said about the second letter. When Larry got in front of the Potter house he was disappointed to see that it was in darkness. It was about ten o'clock, and he knew the family was in the habit of retiring early, especially since Mr. Potter's disappearance. As he strolled past on the other side of the street, looking in vain for a glimmer of light, or the sight of a girlish face against the window pane, he passed into the deep shadow cast by a big tree on which shone an electric arc light in front of the Potter house. The blackness was quite deep, in contrast to the illumination on both sides of the tree, for electric lamps have the property of casting dense shadows. If Larry had been looking straight in front of him perhaps it would not have happened, but he was staring at where Grace lived, and the first thing he knew he had walked full tilt into a man who was hiding in the darkness behind the big tree. "Oh--ugh!" grunted Larry, for the breath was knocked from his body by the sudden impact. "What's the matter? What are you doing?" inquired the man angrily. "Why don't you look where you're going?" The collision had swung him out of the shadow into the light, where he stood blinking. Larry recovered his breath, and then, at the sight of the man, gave a low-voiced cry of astonishment. "Mr. Sullivan!" he exclaimed. "Oh, it's you, is it, Dexter!" remarked the politician. "Are you following me? Are you spying on me? If you are I'll have you arrested!" "I'm not following you or spying on you!" retorted Larry. "But you seem to be hiding here. What do you want? What are you in front of Mr. Potter's house for?" He was determined to follow up his advantage, and to show Sullivan that he was not in the least intimidated by him. Clearly there was something in the wind when the district political leader was hiding behind trees watching the house of the missing millionaire. "Look here!" exclaimed Sullivan, and he had moved back until he was in the shadow. "You go along and mind your own business; do you hear? Move along now!" "I guess I have as good a right as you have to remain on the street. And this sidewalk is just as public as any in New York, even if it is in the millionaire section. What are you hiding for? Do you expect to see Mr. Potter come walking down the steps? If you do I'll wait, too. I'd like to see him."