I was moving off towards the house again when he suddenly called me back.

“I say, what was the end of that message? Say it over again, will you?”

“ ‘Find the extra coffee-cup, and you can rest in peace.’ Are you sure you don’t know what it means?” I asked him earnestly.

He shook his head.

“No,” he said musingly, “I don’t. I⁠—I wish I did.”

The boom of the gong sounded from the house, and we went in together. Poirot had been asked by John to remain to lunch, and was already seated at the table.