There was a moment’s pause, then the millionaire’s voice came through.

“Is that you, M. Poirot? I just wanted to tell you that Mason came to me now of her own accord. She has been thinking it over, and she says that she is almost certain that the man at Paris was Derek Kettering. There was something familiar about him at the time, she says, but at the minute she could not place it. She seems pretty certain now.”

“Ah,” said Poirot, “thank you, M. Van Aldin. That advances us.”

He replaced the receiver, and stood for a minute or two with a very curious smile on his face. George had to speak to him twice before obtaining an answer.

“Eh?” said Poirot. “What is that that you say to me?”

“Are you lunching here, sir, or are you going out?”