“ M. Papopolous,” he said, “I am going to lay my cards upon the table. The original of these jewels was stolen from Madame Kettering on the Blue Train. Now I will say to you first this: I am not concerned with the recovery of these jewels. That is the affair of the police. I am working not for the police but for M. Van Aldin. I want to lay hands on the man who killed Madame Kettering. I am interested in the jewels only in so far as they may lead me to the man. You understand?”

The last two words were uttered with great significance. M. Papopolous, his face quite unmoved, said quietly:

“Go on.”

“It seems to me probable, Monsieur, that the jewels will change hands in Nice⁠—may already have done so.”