"Didn't I call out to catch the thief?" answered the youth, sharply. "Let me go. If you weren't so dead slow, you'd be doing something, instead of standing there looking at the moon." And on he went again, the officer shaking his fist after him, half of the opinion that Walter was trying to joke him. At this hour of the evening the street was far from crowded, and Walter kept the man ahead in sight with comparative ease. Four blocks were covered, when the fellow paused and looked back. Seeing he was being followed, he turned and darted into a small side street. Here were a number of warehouses and several tenements. The door to one of the latter stood open, and he lost no time in seeking the shelter of the dark hallway. "That's the time I made a bad break," he muttered thickly. "When I came up to Boston with that stuff I reckoned I was safe. I wonder if he'll follow me to here? He had better not, unless he wants a broken head." In the meantime, Walter had reached the corner of the side street and come to a halt. The narrow thoroughfare was but dimly lighted, and not a soul was in sight. "He turned in here,--I am certain of that," said the boy to himself. "More than likely he is in hiding in some dark corner. I wonder if I hadn't better call an officer?" With this intention he gazed around, but no policeman was in view, and he did not think it advisable to go back for the guardian of the peace before encountered. He entered the side street slowly and cautiously, peering into every nook and corner, and behind every bill-board, box, and barrel as he moved along. He had just passed the tenement where the man was in hiding when the sounds of muffled voices broke upon his ears, and the front door was thrown back with a bang. "Who are you, and what are you doing in here?" came in an unmistakable Irish voice. "Excuse me--I--I made a mistake," was the answer; and now Walter recognized the tones of the fellow who had the watch. "I am looking for a man named Harris." "Well, he doesn't live here,--so you had better get out." "Will you--er--tell me who lives next door?" asked the man Walter was after, in a lower tone, evidently wishing to gain time ere leaving the building. "A man named Casey and another named Barton live there. There ain't a Harris on the block. If you----" "Hold him, please," burst in Walter, mounting the tenement steps. "He has a watch that was stolen from my uncle." "Shut up, boy!" answered the man fiercely. "My watch is my own, and this is all a mistake." "There is no mistake. Hold him, will you?" "I've got him," came from the gloom of the hallway. "I thought he was a sneak or something by the way he was tip-toeing around here."