Poirot was sobered at once.

"Come, come, my friend," he said, slipping his arms through mine. "Ne vous fachez pas! Allow me to interest myself in my coffee-cups, and I will respect your coco. There! Is it a bargain?"

He was so quaintly humorous that I was forced to laugh; and we went together to the drawing-room, where the coffee-cups and tray remained undisturbed as we had left them.

Poirot made me recapitulate the scene of the night before, listening very carefully, and verifying the position of the various cups.

"So Mrs. Cavendish stood by the tray--and poured out. Yes. Then she came across to the window where you sat with Mademoiselle Cynthia. Yes. Here are the three cups. And the cup on the mantel-piece, half drunk, that would be Mr. Lawrence Cavendish's. And the one on the tray?"

"John Cavendish's. I saw him put it down there."

"Good. One, two, three, four, five--but where, then, is the cup of Mr. Inglethorp?"

"He does not take coffee."

"Then all are accounted for. One moment, my friend."