Realizing his helplessness in the almost total darkness, he bent down, groping about in an unsuccessful effort to recover the searchlight. And then, with a loud cry, a heavy body projected itself upon him, grasping wildly at his hair. An arm, clothed in some silken material, encircled his throat. He felt himself choking. And at the same moment a strange and irrational terror seized him. He seemed in the grasp of something uncanny, something inhuman, in spite of its very human cries. With a shudder he sprang to his feet, unable to locate the missing electric torch, and shaking the shrieking figure from him, plunged toward the window by which he had entered. It was not alone the surprise, the nameless terror of the thing, that sent Duvall headlong from the room. He fully realized that the noise of the encounter, the shrieks of his assailant, would quickly bring the other inmates of the house to the room. He had no wish to be discovered there--his entrance had been too irregular, too illegal, for that. With extraordinary rapidity he flung himself through the window and without waiting to observe the results of his intrusion, sped swiftly across the roofs of the two buildings, up the steps to the attic roof, and from there, by means of the ladder, to the roof of the apartment building. The janitor sat where he had left him, smoking a pipe. Duvall looked back. Lights were visible in the room he had just left. He saw a figure, one that closely resembled Marcia Ford, cross the lighted area of the window. There was a second figure with her--smaller, shorter, he thought. Who--what was it that had attacked him? He stood in a daze, unable to grasp the meaning of the experience through which he had just passed. The janitor took his pipe from his mouth and rose. "Find what you were looking for?" he asked with a grin. Duvall shook his head. "No," he said. "Not exactly. But I'm on the track of it." "Want the ladder any more?" "No, not to-night." He assisted the man to draw it up to the roof. A few moments later he had reached the sidewalk. He glanced at his watch. It was just eight o'clock. As he walked toward the entrance of the house at No. 162, the front door opened, and a woman came out. Duvall quickened his pace, but the woman was also apparently in a great hurry. She ran swiftly across the sidewalk, and sprang into a cab which stood beside the curb. Duvall was able to get but a fleeting glance at her, but that glance was enough to convince him that she was the mysterious prisoner who had so neatly given him the slip while in the cab the night before. He sprang forward with a cry, but before he had come within ten feet of the cab, the vehicle dashed off and proceeded at a rapid rate up the street.