； I can see that。 And why not？ Is not the affair of the Blue Train our own 'Roman Policier'？〃
〃Yes； there are things I should like to ask you。〃
〃Eh bien？〃
Katherine looked up with a sudden air of resolution。
〃What were you doing in Paris； Monsieur Poirot？〃
Poirot smiled slightly。
〃I made a call at the Russian Embassy。〃
〃Oh。〃
〃I see that that tells you nothing。 But I will not be a human oyster。 No； I will lay my cards on the table； which is assuredly a thing that oysters do not do。 You suspect； do you not； that I am not satisfied with the case against Derek Kettering？〃
〃That is what I have been wondering。 I thought； in Nice； that you had finished with the case。〃
〃You do not say all that you mean； Mademoiselle。 But I admit everything。 It was I … my researches … which placed Derek Kettering where he is now。 But for me the Examining Magistrate would still be vainly trying to fasten the crime on the te de la Roche。 Eh bien； Mademoiselle； what I have done I do not regret。 I have only one duty … to discover the truth； and that way led straight to Mr Kettering。 But did it end there？ The police say yes； but I； Hercule Poirot； am not satisfied。〃
He broke off suddenly。 〃Tell me； Mademoiselle； have you heard from Mademoiselle Lenox lately？〃
〃One very short； scrappy letter。 She is； I think； annoyed with me for ing back to England。〃
Poirot nodded。
〃I had an interview with her the night that Monsieur Kettering was arrested。 It was an interesting interview in more ways than one。〃
Again he fell silent； and Katherine did not interrupt his train of thought。
〃Mademoiselle；〃 he said at last； 〃I am now on delicate ground； yet I will say this to you。 There is； I think； someone who l