Mr. Shelton's first impulse, after his interesting interview with Mrs. Mason, had been to rush into town, secure a squad of police, and make an immediate raid upon the house of which he had heard such suspicious tales. Had he obeyed this hasty prompting of his mind, all would have gone well, and this story of mine might have been concluded in a very few more chapters. But the famous detective in his eventful career had usually found it advantageous to think twice before he acted. He did so in this case, and his second thought resulted briefly in this: He did not consider that he had as yet sufficient to warrant him in taking the step he at first proposed to himself. He had no actual grounds for suspicion except the fact that Doctor Pratt and Harold Colville had entered the house, and remained there a seemingly rather long time for a professional call from a busy physician whose time was limited. Mrs. Mason's information was all gained from the oftentimes worthless gossip of a country neighborhood, and could scarcely be depended on as reliable evidence. The mysterious case of the young girl who had been befriended by the worthy woman might have no connection with the old house and its inhabitants as he had hastily concluded at first. Considering all the circumstances, the cautious detective determined to wait before taking any decided step, and in the meantime to learn more of the mysterious house if possible. His pursuit of Pratt and Colville in the next few days took him in entirely different directions, but resulted in nothing satisfactory. In the meantime Mrs. Mason's gossip about the old house and its wicked inhabitants haunted him persistently. He could not rid himself of the thought. It abode with him by day, and in his sleep assumed the guise of night-mare. The old house actually preyed upon him. After a few days of this troubled thinking he came to a firm determination. "I will go out there and make some plausible excuse for entering, if I can possibly do so," he said, to himself, "and once inside, I will try to find out whether there is ready ground for suspicion and inquiry." His mind was relieved when he had resolved upon his course. Accordingly, he mounted his black horse and set out that very evening on his quest. He felt disappointed when he passed the tiny cottage of Mrs. Mason and saw the door closed. He missed the pleasant face from the doorway, but the evening was quite cool, and the good soul was, no doubt, knitting inside by her lonely hearthstone. Within half a mile of his destination he encountered a lady walking rapidly in the dusty road. She was graceful in figure, fashionable in dress, but her thickly-veiled face gave no hint of her identity. The detective looked after her with no little curiosity.