The little job of getting the old-fashioned rear window open was a mere nothing to the experienced O'Hara, and in a moment he was inside the house. His feet struck soft carpet. Catlike, he stepped to one side in order to prevent any hidden eyes from perceiving his form silhouetted in the dim light of the open window. He dared not use his flashlight for fear that the circle of light would betray his position, thus making him an excellent target for possible bullets. Following the wall closely he managed to circle the room without mishap. His searching fingers finally came in contact with a door frame, and he breathed a sigh of relief. Here there was nothing to bar his progress except some moth-eaten portieres. These he brushed aside. The room which he now entered was probably the same into which the Professor had ushered Handlon and Perry the day before. There being still no sign of life about, the reporter decided to throw caution to the winds. He brought his flash into play. Quickly casting the powerful beam around the chamber he examined the place with an all-searching glance. * * * * * Nothing. With a stifled oath he turned his attention to the other rooms in the immediate vicinity. The brilliant light revealed not the slightest trace of a person, living or dead. The sound must have come from the second story or from the cellar. He decided on the upper floor. Feverish with impatience because of the valuable time he had already lost, he bounded up the heavily carpeted stairs two at a time. Now to his keen ears came certain faint sounds which told him that he was on the right track. Before him extended a long, dusty hall, terminating in a single heavy door. Several other doors opened at intervals along the corridor. One or two of these were open, and he threw the beam from his flash hastily into one after another of them. He saw only dusty and mildewed chamber furnishings of an ancient massive style. Suddenly he pricked up his ears. The door ahead of him was creaking slowly open. Instantly he extinguished his torch and leaped into the nearest room. Whoever was opening that end door was carrying a lamp. What if the Professor had accomplices who might discover him and overpower him by force of numbers! O'Hara drew the automatic from his pocket, deriving a comforting assurance from the feel of the cold steel. Here was something no man could resist could he but get it into action. The light was now nearly abreast of his door, and for a sickening instant he thought the prowler was coming into the room. He held his breath. Now the lamp was at the open door, and now it was quickly withdrawn. After a breathless second he tip-toed forward and peered cautiously down the hallway.