Katherine looked rather astonished. “I don’t think so,” she said. Poirot drew from his pocket a cigarette case of soft blue leather, with the initial “K” on it in gold.

“No, that is not mine,” Katherine said.

“Ah, a thousand apologies. It was doubtless Madame’s own. ‘K,’ of course, stands for Kettering. We were doubtful, because she had another cigarette case in her bag, and it seemed odd that she should have two.” He turned to Derek suddenly. “You do not know, I suppose, whether this was your wife’s case or not?”

Derek seemed momentarily taken aback. He stammered a little in his reply: “I⁠—I don’t know. I suppose so.”

“It is not yours by any chance?”

“Certainly not. If it were mine it would hardly have been in my wife’s possession.”

Poirot looked more ingenuous and childlike than ever.