“No need to trouble Butterworth,” exclaimed Anthony, “we know our rooms. Here’s mine—there’s yours, Daventry. Good-night!” Anthony walked to the window and opened it. He was fond of darkness and it was just beginning to get dark. Darkness and its attendant tranquillity he always found invaluable conditions for the process of concentration—he had often discovered the solution to a mystifying problem out of this communion. He smoked a cigarette through and lit another. “What was it,” he said to himself as he stood there by the open window, “that caused Stewart to come downstairs and enter the library? What happened in the library to make him scrawl the message that he described as ‘urgent’?” He commenced a third cigarette. “And who trod softly behind as he sat there writing—and killed him?” He undressed and got into bed. “A pretty little problem—especially when we think of the Hanover Galleries affair on top.” That was his last conscious thought before he slept. He had the knack of getting to sleep almost instantaneously and also the complementary faculty of awaking at the slightest sound. He was destined to awake suddenly that night. And he knew instantly and instinctively what had awakened him—a stealthy step had gone past his bedroom door—he was certain of it! He looked at the luminous face of his wrist-watch. “Twenty-two minutes past one,” he muttered. “Not an ordinary time for legitimate night-wanderings.” He tiptoed to his bedroom door and drew it very slightly ajar; then listened intently for what seemed like ages. It was very quiet beneath him. Had the step been on its way back? Suddenly he heard a sound that sent his heart racing perilously—somebody was ascending the stairs! He shut the door silently and held the handle tight. The step passed—almost noiselessly. Anthony waited a second, then pulled his door gently open, and looked out on to the corridor. He was just able to distinguish the figure of a man, entering the room next but one. A man—slim and of good height. Judged by his walk—comparatively young. Anthony whistled very softly, as he sat on the side of his bed to think things over. “Now, who the devil was that?” he muttered, “and why does he wander o’ nights?” In the morning at breakfast his first query was answered. “Let me introduce you,” said Charles Stewart. “Mr. Bathurst—Mr. Morgan Llewellyn—my late father’s secretary.” CHAPTER X The Incident of the Boot-Boy’s Bicycle