“But why take the jewels?”

“To make the crime appear an ordinary one committed by train robbers. Otherwise suspicion might have fallen on him straight away.”

“If that is so, what has he done with the rubies?”

“That remains to be seen. There are several possibilities. There is a man in Nice who may be able to help, the man I pointed out at the tennis.”

He rose to his feet and Van Aldin rose also and laid his hand on the little man’s shoulder. His voice when he spoke was harsh with emotion.

“Find Ruth’s murderer for me,” he said, “that is all I ask.”

Poirot drew himself up.

“Leave it in the hands of Hercule Poirot,” he said superbly; “have no fears. I will discover the truth.”