As he listened to Mandy's halting footsteps growing fainter and fainter as she climbed wearily upstairs, Mitchell contemplated the large square room filled with "period" furniture. The old brocades were shabby and the rugs worn, but there was an indefinable atmosphere of the refinement of a bygone generation which time and neglect had not destroyed. Mitchell raised the shades in the windows overlooking Q Street and peered outside. No automobile except his own, waiting at the curb, was in sight. Satisfied on that point, he opened the window ever so slightly that he might be sure and hear a car drive up to the door, and then, to occupy his time, he wandered about the room and examined the many pieces of bric-a-brac on the mantel and in cabinets. One cabinet in particular attracted his attention. It was a fine piece of Florentine workmanship and remarkably well preserved. The floor of the cabinet held miniatures of, presumably, ancestors of Miss Susan Baird, and after a cursory glance at them, Mitchell scanned the articles on the glass shelves. A set of carved ivory chessmen awoke his admiration and observing that the key was in the door of the cabinet he opened it. After examining the little chessmen, he turned his attention to the ivory checkers and then to the two ivory cups for holding dice. The carving on them was very fine and to see them better Mitchell carried them to the gas light. Glancing at the red dice cup, he was surprised to find cotton stuffed inside it. Setting down the other cup, Mitchell pulled out the layer of cotton and found a small bottle standing upright. It was held in the center of the cup by cotton packed around it. Drawing out the bottle he held it up to the light. It was almost empty. Mitchell pulled out the glass stopper and sniffed at the contents. A distinct smell of bitter almonds caused him to draw in his breath sharply. "Prussic acid!" he muttered. "By God! And Miss Susan Baird was poisoned with a dose of it." There was no label on the small phial. Taking out his handkerchief Mitchell replaced the glass stopper, and wrapped his handkerchief about the phial. Putting it carefully in his pocket, he paused for a moment to take another look at the dice cups, then replaced them in the cabinet. He and two of his assistants had made a complete and searching examination of the parlor immediately after the discovery of the crime. Mitchell was willing to swear that neither cotton nor phial had been in the dice cup then. Who had hidden the incriminating evidence there? Who had had the opportunity to do so? Kitty Baird....