‘So, then to sum up, there were four points of note against Marthe Daubreuil:
(1) Marthe Daubreuil could have overheard Renauld’s plans.’
(2) Marthe Daubreuil had a direct interest in causing Renauld’s death.
(3) Marthe Daubreuil was the daughter of the notorious Madame Beroldy who in my opinion was morally and virtually the murderess of her husband, although it may have been Georges Conneau’s hand which struck the actual blow.
(4) Marthe Daubreuil was the only person, besides Jack Renauld, likely to have the third dagger in her possession.’
Poirot paused and cleared his throat. ‘Of course, when I learned of the existence of the other girl, Bella Duveen, I realized that it was quite possible that she might have killed Renauld. The solution did not commend itself to me, because, as I pointed out to you, Hastings, an expert, such as I am, likes to meet a foeman worthy of his steel. Still, one must take crimes as one finds them, not as one would like them to be. It did not seem very likely that Bella Duveen would be wandering about carrying a souvenir paper knife in her hand, but of course she might have had some idea all the time of revenging herself on Jack Renauld. When she actually came forward and confessed to the murder, it seemed that all was over. And yet—I was not satisfied, mon ami. I was not satisfied . . . .’
‘I went over the case again minutely, and I came to the same conclusion as before. If it was not Bella Duveen, the only other person who could have committed the crime was Marthe Daubreuil. But I had not one single proof against her!’
‘And then you showed me that letter from Mademoiselle Dulcie, and I saw a chance of settling the matter once for all. The original dagger was stolen by Dulcie Duveen and thrown into the sea—since, as she thought, it belonged to her sister. But if, by any chance, it was not her sister’s, but the one given by Jack to Marthe Daubreuil—why then, Bella Duveen’s dagger would be still intact! I said no word to you, Hastings (it was no time for romance), but I sought out Mademoiselle Dulcie, told her as much as I deemed needful, and set her to search among the effects of her sister.’
‘Imagine my elation, when she sought me out (according to my instructions) as Miss Robinson with the precious souvenir in her possession!’
‘In the meantime I had taken steps to force Mademoiselle Marthe into the open. By my orders, Madame Renauld repulsed her son, and declared her intention of making a will on the morrow which should cut him off from ever enjoying even a portion of his father’s fortune. It was a desperate step, but a necessary one, and Madame Renauld was fully prepared to take the risk—though unfortunately she also never thought of mentioning her change of room, I suppose she took it for granted that I knew. All happened as I thought.’
‘Marthe Daubreuil made a last bold bid for the Renauld millions—and failed!’
‘What absolutely bewilders me,’ I said, ‘is how she ever got into the house without our seeing her. It seems an absolute miracle. We left her behind at the Villa Marguerite, we go straight to the Villa Genevieve—and yet she is there before us!’
‘Ah, but we did not leave her behind. She was out of the Villa Marguerite by the back way while we were talking to her mother in the hall. That is where, as the Americans say, she “put it over” on Hercule Poirot!’
‘But the shadow on the blind? We saw it from the road.’
‘Eh bien, when we looked up, Madame Daubreuil had just had time to run upstairs and take her place.’
‘Madame Daubreuil?’
‘Yes. One is old, and one is young, one dark, and one fair, but, for the purpose of a silhouette on a blind, their profiles are singularly alike. Even I did not suspect—triple imbecile that I was! I thought I had plenty of time before me—that she would not try to gain admission to the villa until much later. She had brains, that beautiful Mademoiselle Marthe Daubreuil.’