They were then at the head of the steps; a woman of slender beauty with a wonderful loose fold of black hair was talking. It seemed to the detective that her voice was fearful, of a pregnant warning, that she was protesting. Nevertheless, the old men entered and the door slammed behind them. Jerome slipped from the taxi and spoke a few words to the driver. A moment later the two men were holding the house under surveillance. They did not have long to wait. The man called Rhamda had asked for fifteen minutes. At the stroke of the second the front door re-opened. Someone was laughing; a melodious enchanting laugh and feminine. A woman was speaking. And then there were two forms in the doorway. A man and a woman. The man was Rhamda Avec, tall, immaculate, black clad and distinguished. The woman, Jerome was not certain that she was the same who opened the door or not; she was even more beautiful. She was laughing. Like her companion she was clad in black, a beautiful shimmering material which sparkled in the sun like the rarest silk. The man glanced carelessly up and down the street for a moment. Then he assisted the lady down the steps and into the taxi. The door slammed; and before the detective could gather his scattered wits they were lost in the city. Jerome was expecting the professor. Naturally when the door opened he looked for the old gentleman and his companion. It was the doctor he was watching, not the other. Though he had no rational reason for expecting trouble he had still his hunch and his intuition. The man and woman aroused suspicion; and likewise upset his calculation. He could not follow them and stay with the professor. It was a moment for quick decision. He wondered. Where was Dr. Holcomb? This was the day he was to deliver his lecture on the Blind Spot. He had read the announcement in the paper on the way back, together with certain comments by the editor. In the lecture itself there was mystery. This strange one, Rhamda, was mixed in the Blind Spot. Undoubtedly he was the essential fact and substance. Until now he had not scented tragedy. Why had Rhamda and the woman come out together? Where was the professor? Where indeed? At the end of a half-hour Jerome ventured across the street. He noted the number 288. Then he ascended the steps and clanged at the knocker. From the sounds that came from inside, the place was but partly furnished. Hollow steps sounded down the hallway, shuffling, like weary bones dragging slippers. The door opened and an old woman, very old, peered out of the crack. She coughed. Though it was not a loud cough it seemed to the detective that it would be her last one; there was so little of her. “Pardon me, but is Dr. Holcomb here?” The old lady looked up at him. The eyes were of blank expressionless blue; she was in her dotage. “You mean--oh, yes, I think so, the old man with the white whiskers. He was here a few minutes ago, with that other. But he just went out, sir, he just went out.”