On each floor lights were burning. As he looked up, he saw Darwin distinctly on the next floor, and he heard him knock on the door of the back room. Darwin knocked a number of times, and no one opened the door. When he started to descend the stairs, Carter walked out, and took up a position in a doorway of a house near the corner. Darwin came out of the tenement, walked to the corner, and halted. Back and forth he moved, and kept looking at the house. The detective saw that he was uneasy. He wondered whom Darwin had come to see. Darwin, after a time, came back to the tenement, and entered again. Carter did not move from his hiding place. His quarry only remained inside a minute or so, and then came out, going back to the corner and halting. Carter came out of the doorway. He strolled up to the corner, and stopped within a few feet of Darwin, who saw and eyed him. Two or three times the man made a movement as if he were going to address Carter. But he hesitated. The detective made no attempt to speak. He looked up and down the street, and appeared unconcerned. Carter wanted to see if Darwin would speak to him. He judged that if he waited long enough the man would do so. Darwin crossed the street, halted a moment, and then came back. He glanced sharply, suspiciously, at Carter. “Excuse me,” he said, as he came to a standstill, “do you live around here?” “Are you addressing me?” the detective asked, in a disguised tone of voice. “I am.” “Oh, well, yes, I live in that house down there,” said Nick, pointing to the tall tenement which Darwin had twice entered. “You do? What floor do you live on?” “The top. Why?” “I want some information about one of the tenants.” “Eh!” Carter bent forward and looked at Darwin. His acting was magnificent. “Say, are you a fly cop?” he asked, with suspicion. “No,” Darwin replied quickly, “I’m not a detective.” “You haven’t got the cut of one.” “No.” “What do you want to know?” “Are you acquainted with a woman named Lena Peters?” “You mean the woman who lives in the back room on the second floor?” “Yes, yes.” “I know her by sight.” “Have you seen her to-night?” “No.” “I’ve been to her room and knocked, but no one seems to be in.” “Did you have an appointment with her?” “Not exactly an appointment.” “Oh!” For a time they were silent. Then Carter said, in an offhand way: “What does Miss Peters do?” “She sings in a concert hall over on the West Side,” Darwin replied. “I often wondered what she worked at to keep her out so late at night.” “Will you see her when she comes in?” “I don’t know.” “Are you going to remain here long?” “All night.” “What for?” “I watch stores on the block.” “Oh!” “Why did you ask that question?” “Will you deliver a message to Lena Peters when she comes home?” “Certainly.” “Tell her that a gentleman named Richard called to see her, and that he wants her to come to his room the first thing after noon.” “Where are your rooms?”