“I always bring two glasses, sir,” said Parker. “Is there anything further?”

“Nothing. I thank you.”

Parker withdrew, dignified to the last.

Poirot stood in the middle of the hall frowning. Flora came down and joined us.

“Has your experiment been successful?” she asked. “I don’t quite understand, you know⁠—”

Poirot smiled admiringly at her. “It is not necessary that you should,” he said. “But tell me, were there indeed two glasses on Parker’s tray that night?”

Flora wrinkled her brows a minute.

“I really can’t remember,” she said. “I think there were. Is⁠—is that the object of your experiment?”