“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?”