“Monsieur, if a doctor walks along the street and an accident happens, does he say, ‘I have retired from my profession, I will continue my walk,’ when there is someone bleeding to death at his feet? If I had been already in Nice, and the police had sent to me and asked me to assist them, I should have refused. But this affair, the good God thrust it upon me.”

“You were on the spot,” said Van Aldin thoughtfully. “You examined the compartment, did you not?”

Poirot nodded.

“Doubtless you found things that were, shall we say, suggestive to you?”

“Perhaps,” said Poirot.

“I hope you see what I am leading up to?” said Van Aldin. “It seems to me that the case against this Comte de la Roche is perfectly clear, but I am not a fool. I have been watching you for this last hour or so, and I realise that for some reason of your own you don’t agree with that theory?”