He walked to the middle of the room and turned slowly about, letting the picture sink into his brain. When he had made the complete circuit, he sat on the edge of the table and shut his eyes. Alec watched him interestedly. “Any luck?” he asked, after a couple of minutes’ silence. Roger opened his eyes. “No,” he admitted, a little ruefully. It is always disappointing after such carefully staged preparations to find that one’s pet trick has failed to work. Roger felt not unlike a conjuror who had not succeeded in producing the rabbit from the top-hat. “Ah!” observed Alec noncommittally. “I can’t see anything different,” said Roger, almost apologetically. “Ah!” Alec remarked again. “Then I suppose that means that nothing is different?” he suggested helpfully. “I suppose so,” Roger admitted. “Now are you going to tell me that this is really devilish significant?” Alec grinned. “Because if you do, I warn you that I shan’t believe you. It’s exactly what I expected. I told you you were making too much fuss about a lot of trifles.” “Shut up!” Roger snapped from the edge of the table. “I’m thinking.” “Oh, sorry!” Roger took no notice of his fellow sleuth’s unprofessionally derisive grin. He was staring abstractedly at the big carved oak chimney-piece. “There’s only one thing that strikes me,” he observed slowly after a little pause, “now I come to think of it. Doesn’t that chimney-piece look somehow a bit lopsided to you?” Alec followed the other’s gaze. The chimney-piece looked ordinary enough. There were the usual pewter plates and mugs set out upon it, and on one side stood a large blue china vase. For a moment Alec stared at it in silence. Then: “I’m blessed if I see anything lopsided about it,” he announced. “How do you mean?” “I don’t know exactly,” Roger replied, still gazing at it curiously. “All I can say is that in some way it doesn’t look quite right to me. Side-heavy, if I may coin a phrase.” “You may,” said Alec kindly. “That is, if you’ll tell me what it means.” “Well, unsymmetrical, if you like that better.” He slapped his knee suddenly. “By Jove! Idiot! I see now. Of course!” He turned a triumphant smile upon the other. “Fancy not noticing that before?” “_What?_” shouted Alec in exasperation. “Why, that vase. Don’t you see?” Alec looked at the vase. It seemed a very ordinary sort of affair. “What’s the matter with it? It looks all right to me.” “Oh, there’s nothing the matter with it,” said Roger airily. “It is all right.” Alec approached the table and clenched a large fist, which he proceeded to hold two inches in front of Roger’s nose. “If you don’t tell me within thirty seconds what you’re talking about, I shall smite you,” he said grimly. “_Hard!_” “I’ll tell you,” said Roger quickly. “I’m not allowed to be smitten before lunch. Doctor’s orders. He’s very strict about it, indeed. Oh, yes; about that vase. Well, don’t you see? There’s only one of it!”