There was the mysterious "Whisperer" and his strange visits at dawn. How did his whisper come to her? She had tried in every way to trap him, but with no success. Did he indeed talk to her "down a beam of light" from the window of a skyscraper a mile away? And could he see that far too? It seemed preposterous. And yet-- Drew Lane had visited the store three times. Always he wore the jaunty clothes of a college boy. But once she had gripped his arm and found it hard as steel. He was a man, no mistaking that, and a city detective of the highest type. Was he the Whisperer? It seemed absurd to suspect him. "We all whisper alike," she had told herself. So, quite unconscious of her surroundings, she walked on, thinking hard. She had covered two blocks when of a sudden she felt a hand on her arm and heard in a low, chilling tone: "Just a moment, please." Next instant she found herself looking into the face of the man who, a half hour before, had so frightened Nida McFay. Never in all her life had she wanted so much to scream. The precious Bible was still under her arm. Those cold eyes were fixed upon her. Ten seconds of thought assured her that she was in no immediate danger. The shops were still open. She was surrounded by friends. In her brief stay on the street she had made many friends. Max Schmalgemeire, the baker, stood in his door; so too did Mamma Lebed, who sold geese. Peter Rapport was turning his hot dogs. Even Madam Jakolev, the gypsy fortune-teller, whom she strongly suspected of carrying a dagger up her sleeve, was a welcome sight at that moment. "I merely wanted to ask you a question." The man was polite enough. "Do you know," his words were distinct and cold, "this girl Nida McFay is a police character?" "Po--Police?" Grace stared. "Practically that. Frank Morrow's is the only place she could sell books in this city. He is stubborn, foolhardy. Just thought I'd warn you. I am J. Templeton Semp, a detective." He tipped his hat and was gone, leaving Grace with a sinking sensation at the pit of her stomach. "A police character!" she whispered. "How could she be?" She was to hear more of Nida next morning, for the "Whisperer" was to be with her once more at dawn. CHAPTER XVII "THE EYE" As we have said, it was dark when Johnny Thompson finally returned to the "Street of Mystery," as he had come to call it. Felix's answer to his excited questioning at an earlier hour had been strange. Yes, he knew where the men were that Johnny had seen in that animated picture--at least, he knew where they had been when Johnny looked at them; they were in the house down the street where he and Johnny had planted wires and instruments. Had Johnny really seen the men? "Seen them!" Johnny fairly raved. "I recognized one of them as surely as if he had been my brother!" "That's fine!" Felix smiled blandly. "That proves the thing will work."