To secure entrance to the room by the usual channels was clearly out of the question. The people at the boarding house would, of course, not permit it. But could he discover the means of communication, whatever they were, between Miss Morton's apartment and the girl's room, he might be able to enter the latter unknown and unobserved. He had thought of attempting this during the afternoon, but realized that he could not hope to accomplish it, in broad daylight, without being seen by the occupants of the neighboring buildings, and perhaps arrested as a burglar or sneak thief. With a last glance down the street, he hastened back to the apartment building and made his way to Mrs. Morton's flat. Passing quickly through Ruth Morton's bedroom, he climbed out upon the fire escape and looked about. Below him were the rear yards of the houses fronting on the next street. To the right he could see the bulk of the apartment building, blocking his view of the avenue beyond. To the left were the rear buildings of the adjoining houses. It was quite dark, the sky was starless, but all about him gleamed the lights in the windows of the neighboring buildings. Neither to the right, nor to the left was there any possible way by which access to the point where he now stood could be gained. From below, it was possible, although his previous examination had showed him both the fact that the newly painted surface of the fire escape was unmarred, and that the ladder at the lower floor was drawn up some nine or ten feet from the ground. He felt certain that Miss Ford had not reached Ruth's room in that way. He glanced upward. The fire escaped stopped at the level of the floor above. To ascend from it to the roof was impossible. Remembering that the top apartment was vacant, Duvall re-entered the building and hunting up the janitor, told him that he desired to get out on the roof. The man remembered him, from his first visit, and the inquiries he had then made about the tenants of the apartment above. "I am making some special inquiries on Mrs. Morton's behalf," he explained. "You can go with me, if you like, to see that I do nothing I shouldn't." The janitor joined in his laugh. "I'm not worrying," he rejoined, "but I'll go along, just the same, to show you the way." He led the detective up one flight of stairs and, going to the end of the outer hall, unlocked and opened a small door beside the elevator shaft. A short spiral staircase was disclosed. Snapping on an electric light, the man ascended the steps, and, after fumbling for a moment with the catch, threw open a trapdoor leading to the roof. In a moment both he and Duvall had climbed out upon the tiled surface. Duvall went to the edge which overlooked the house adjoining, and peered down. He at once saw something that interested him.