up。〃
His eyes came gently round to the girl。 She had pushed her cup and plate aside； and with both elbows on the table and her chin resting on her hands was listening eagerly。 Still keeping an eye on her he went on：
〃I am in Paris at the time。 You send for me。 You place yourself in my hands。 If I restore to you that … article； you say I shall earn your undying gratitude。 Eh bien！ I did restore it to you。〃
A long sigh came from M。 Papopolous。
〃It was the most unpleasant moment of my career；〃 he murmured。
〃Seventeen years is a long time；〃 said Poirot thoughtfully； 〃but I believe that I am right in saying； Monsieur； that your race does not forget。〃
〃A Greek？〃 murmured Papopolous； with an ironical smile。
〃It was not as a Greek I meant；〃 said Poirot。
There was a silence； and then the old man drew himself up proudly。
〃You are right； M。 Poirot；〃 he said quietly。 〃I am a Jew。 And； as you say； our race does not forget。〃
〃You will aid me then？〃
〃As regards the jewels； Monsieur； I can do nothing。〃
The old man； as Poirot had done just now； picked his words carefully。
〃I know nothing。 I have heard nothing； but I can perhaps do you a good turn … that is if you are interested in racing。〃
〃Under certain circumstances I might be；〃 said Poirot； eyeing him steadily。
〃There is a horse running at Longchamps that would； I think； repay attention。 I cannot say for certain； you understand； this news passed through so many hands。〃
He stopped； fixing Poirot with his eye； as though to make sure that the latter was prehending him。
〃Perfectly； perfectly；〃 said Poirot； nodding。
〃The name of the horse；〃 said M。 Papopolous； leaning back and joining the tips of his fingers together； 〃is the Marquis。 I think； but I am not sure； that it is an English horse； eh； Zia？〃
〃I think so too；〃 said the girl。
Poirot got up briskly。
〃I thank you； Monsieur；〃 he said。 〃It is a great thing to have what the English call a tip from the stable。 Au revoir； Monsieur； and many thanks。〃
He turned to the girl。
〃Au revoir； Mademoiselle Zia。 It seems to me but yesterday that I saw you in Paris。 One would say that two years had passed at most。〃
〃There is a difference between sixteen and thirty…three；〃 said Zia ruefully。
〃Not in your case；〃 declared Poirot gallantly。 〃You and your father will perhaps dine with me one night。〃
〃We shall be delighted；〃 replied Zia。
〃Then we will arrange it；〃 declared Poirot； 〃and now … je me sauve。〃
Poirot walked along the street humming a little tune to himself。 He twirled his stick with a jaunty air； once or twice he smiled to himself quietly。 He turned into the first Bureau de Poste he came to and sent off a telegram。
He took some time in wording it； but it was in code and he had to call upon his memory。 It purported to deal with a missing scarf…pin； and was addressed to Inspector Japp； Scotland Yard。
Decoded； it was short and to the point。 〃Wire me everything known about man arquis。〃
Chapter 23
A NEW THEORY
It was exactly eleven o'clock when Poirot presented himself at Van Aldin's hotel。 He found the millionaire alone。
〃You are punctual； M。 Poirot；〃 he said； with a smile； as he rose to greet the detective。
〃I am always punctual；〃 said Poirot。 〃The exactitude … always do I observe it。 Without order and method …〃
He broke off。 〃Ah； but it is possible that I have said these things to you before。 Let us e at once to the object of my visit。〃
〃Your little idea？〃
〃Yes； my little idea。〃 Poirot smiled。 〃First of all； Monsieur； I should like to interview once more the maid； Ada Mason。 She is here？〃
〃Yes； she's here。〃
〃Ah！〃
Van Aldin looked at him curiously。 He rang the bell； and a messenger was dispatched to find Mason。
Poirot greeted her with his usual politeness； which was never without effect on that particular class。
〃Good afternoon； Mademoiselle；〃 he said cheerfully。 〃Be seated； will you not； if Monsieur permits。〃
〃Yes； yes； sit down； my girl；〃 said Van Aldin。
〃Thank you； sir；〃 said Mason primly； and she sat down on the extreme edge of a chair。 She looked bonier and more acid than ever。
〃I have e to ask you yet more questions；〃 said Poirot。 〃We must get to the bottom of this affair。 Alan in the train。 You have been shown the te de la Roche。 You say that it is possible he was the man； but you are not sure。〃
〃As I told you； sir； I never saw the gentleman's face。 That is what makes it so difficult。〃
Poirot beamed and nodded。
〃Precisely； exactly。 I prehend well the difficulty。 Now； Mademoiselle； you have been in the service of Madame Kettering two months； you say。 During that time； how often did you see your master？〃
Mason reflected a minute or two； and then said：
〃Only twice； sir。〃
〃And was that near to； or far away？〃
〃Well once； sir； he came to Curzon Street。 I was upstairs； and I looked over the banisters and saw him in the hall below。 I was a bit curious like； you understand； knowing the way things … er … were。〃 Mason finished up with her discreet cough。
〃And the other time？〃
〃I was in the Park； sir； with Annie … one of the housemaids； sir； and she pointed out the master to me walking with a foreign lady。〃
Again Poirot nodded。
〃Now listen； Mason； this man whom you saw in the carriage talking to your mistress at the Gare de Lyon； how do you know it was not your master？〃
〃The master； sir？ Oh； I don't think it would have been。〃
〃But you are not sure；〃 Poirot persisted。
〃Well … I never thought of it； sir。〃
Mason was clearly upset at the idea。
〃You have heard that your master was also on the train。 What more natural than that it should be he who came along the corridor。〃
〃But the gentleman who was talking to the mistress must have e from outside； sir。 He was dressed for the street。 In an overcoat and soft hat。〃
〃Just so； Mademoiselle； but reflect a minute。 The train has just arrived at the Gare de Lyon。 Many of the passengers promenade themselves upon the quay。 Your mistress was about to do so； and for that purpose had doubtless put on her fur coat； eh？〃
〃Yes； sir；〃 agreed Mason。
〃Your master； then； does the same。 The train is heated； but outside in the station it is cold。 He puts on his overcoat and his hat and he walks along beside the train； and looking up at the lighted windows he suddenly sees Madame Kettering。 Until then he has had no idea that she was on the train。 Naturally； he mounts the carriage and goes to her partment。 She gives an exclamation of surprise at seeing him and quickly shuts the door between the two partments since it is possible that their conversation may be of a private nature。〃
He leaned back in his chair and watched the suggestion slowly take effect。 No one knew better than Hercule Poirot that the class to which Mason belongs cannot be hurried。
He must give her time to get rid of her own preconceived ideas。 At the end of three minutes she spoke：
〃Well； of course； sir； it might be so。 I never thought of it that way。 The master is tall and dark； and just about that build。 It was seeing the hat and coat that made me say it was a gentleman from outside。 Yes； it might have been the master。 I would not like to say either way； I am sure。〃
〃Thank you very much； Mademoiselle。 I shall not require you any further。 Ah； just one thing more。〃 He took from his pocket the cigarette case he had already shown to Katherine。 〃Is that your mistress's case？〃 he said to Mason。
〃No； sir； it is not the mistress's … at least …〃
She looked suddenly startled。 An idea was clearly working its way to the forefront of her mind。
〃Yes；〃 said Poirot encouragingly。
〃I think； sir … I can't be sure； but I think … it is a case that the mistress bought to give to the master。〃
〃Ah；〃 said Poirot in a nonmittal manner。
〃But whether she ever did give it to him or not； I can't say； of course。〃
〃Precisely；〃 said Poirot； 〃precisely。 That is all； I think； Mademoiselle。 I wish you good afternoon。〃
Ada Mason retired discreetly； closing the door noiselessly behind her。
Poirot looked across at Van Aldin； a faint smile upon his face。 The millionaire looked thunderstruck。
〃You think … you think it was Derek？〃 he queried； 〃but … everything points the other way。 Why； the Count has actually been caught red…handed with the jewels on him。〃
〃No。〃
〃But you told me …〃
〃What did I tell you？〃
〃That story about the jewels。 You showed them to me。〃
〃No。〃
Van Aldin stared at him。
〃You mean to say you didn't show them to me。〃
〃No。〃
〃Yesterday … at the tennis？〃
〃No。〃
〃Are you crazy； M。 Poirot； or am I？〃
〃Neither of us is crazy；〃 said the detective。 〃You ask me a question； I answer it。 You say have I not shown you the jewels that day？ I reply … no。 What I showed you； Van Aldin； was a first…class imitation； not to be distinguished except by an expert from the real ones。〃
Chapter 24
POIROT GIVES ADVICE
It took the millionaire some few minutes to take the thing in。 He stared at Poirot as though dumbfounded。 The little Belgian nodded at him gently。
〃Yes；〃 he said； 〃it alters the position； does it not？〃
〃Imitation！〃
He leaned forward。
〃All along； M。 Poirot； you have had this idea？ All along this is what you have been driving at？ You never believed that the te de la Roche was the murderer？〃
〃I have had doubts；〃 said Poirot quietly。 〃I said as much to you。 Robbery with violence and murder …〃 he shook his head energetically … 〃no； it is difficult to picture。 It does not harmonize with the personality of the te de la Roche。〃
〃But you believe that he meant to steal the rubies？〃
〃Certainly。 There is no doubt as to that。 See； I will recount to you the affair as I see it。 The te knew of the rubies and he laid his plans accordingly。 He made up a romantic story of a book he was writing； so as to induce your daughter to bring them with her。 He provided himself with an exact duplicate。 It is clear； is it not； that substitution is what he was after。 Madame； your daughter； was not an expert on jewels。 It would probably be a long time before she discovered what had occurred。 When she did so … well … I do not think she would prosecute the te。 Too much would e out。 He would have in his possession various letters of hers。 Oh yes； a very safe scheme from the te's point of view … one that he has probably carried out before。〃
〃It seems clear enough； yes；〃 said Van Aldin musingly。
〃It accords with the personality of the te de la Roche；〃 said Poirot。
〃Yes； but now …〃 Van Aldin looked searchingly at the other。 〃What actually happened？ Tell me that； M。 Poirot。〃
Poirot shrugged his shoulders。
〃It is quite simple；〃 he said； 〃someone stepped in ahead of the te。〃
There was a long pause。
Van Aldin seemed to be turning things over in his mind。 When he spoke it was without beating about the bush。
〃How long have you suspected my son…in…law； M。 Poirot？〃
〃From the very first。 He had the motive and the opportunity。 Everyone took for granted that the man in Madame's partment in Paris was the te de la Roche。 I thought so； too。 Then you happened to mention that you had once mistaken the te for your son…in…law。 That told me that they