‘Geraldine would not hear of my leaving,’ said Miss Carroll. ‘She begged me to stay on. And really, at a time like this, the poor child needs someone. If she needs nothing else, she needs a buffer. And I can assure you, when need be, I make a very efficient buffer, M. Poirot.’

Her mouth took on a grim line. I felt that she would have a short way with reporters or news hunters.

‘Mademoiselle, you have always seemed to me the pattern of efficiency. The efficiency, I admire it very much. It is rare. Mademoiselle Marsh no, she has not got the practical mind.’

‘She’s a dreamer,’ said Miss Carroll. ‘Completely impractical. Always has been. Lucky she hasn’t got her living to get.’

‘Yes, indeed.’

‘But I don’t suppose you came here to talk about people being practical or impractical. What can I do for you, M. Poirot?’

I do not think Poirot quite liked to be recalled to the point in this fashion. He was somewhat addicted to the oblique approach. With Miss Carroll, however, such a thing was not practicable. She blinked at him suspiciously through her strong glasses.

‘There are a few points on which I should like definite information. I know I can trust your memory, Miss Carroll.’

‘I wouldn’t be much use as a secretary if you couldn’t,’ said Miss Carroll grimly.

‘Was Lord Edgware in Paris last November?’

‘Yes.’

‘Can you tell me the date of his visit?’

‘I shall have to look it up.’

She rose, unlocked a drawer, took out a small bound book, turned the pages and finally announced:

‘Lord Edgware went to Paris on November 3rd and returned on the 7th. He also went over on November 20th and returned on December 4th. Anything more?’

‘Yes. For what purpose did he go?’

‘On the first occasion he went to see some statuettes which he thought of purchasing and which were to be auctioned later. On the second occasion he had no definite purpose in view so far as I know.’

‘Did Mademoiselle Marsh accompany her father on either occasion?’

‘She never accompanied her father on any occasion, M. Poirot. Lord Edgware would never have dreamed of such a thing. At that time she was at a convent in Paris, but I do not think her father went to see her or took her out – at least it would surprise me very much if he had.’

‘You yourself did not accompany him?’

‘No.’

She looked at him curiously and then said abruptly:

‘Why are you asking me these questions, M. Poirot? What is the point of them?’

Poirot did not reply to this question. Instead he said:

‘Miss Marsh is very fond of her cousin, is she not?’

‘Really, M. Poirot, I don’t see what that has got to do with you.’

‘She came to see me the other day! You knew that?’ 

‘No, I did not.’ She seemed startled. ‘What did she say?’

‘She told me – though not in actual words – that she was very fond of her cousin.’

‘Well, then, why ask me?’

‘Because I seek your opinion.’

This time Miss Carroll decided to answer.

‘Much too fond of him in my opinion. Always has been.’

‘You do not like the present Lord Edgware?’

‘I don’t say that. I’ve no use for him, that’s all. He’s not serious. I don’t deny he’s got a pleasant way with him. He can talk you round. But I’d rather see Geraldine getting interested in someone with a little more backbone.’

‘Such as the Duke of Merton?’

‘I don’t know the Duke. At any rate, he seems to take the duties of his position seriously. But he’s running after that woman – that precious Jane Wilkinson.’

‘His mother–’

‘Oh! I dare say his mother would prefer him to marry Geraldine. But what can mothers do? Sons never want to marry the girls their mothers want them to marry.’

‘Do you think that Miss Marsh’s cousin cares for her?’

‘Doesn’t matter whether he does or doesn’t in the position he’s in.’

‘You think, then, that he will be condemned?’ 

‘No, I don’t. I don’t think he did it.’

‘But he might be condemned all the same?’

Miss Carroll did not reply.

‘I must not detain you.’ Poirot rose. ‘By the way, did you know Carlotta Adams?’

‘I saw her act. Very clever.’

‘Yes, she was clever.’ He seemed lost in meditation. ‘Ah! I have put down my gloves.’

Reaching forward to get them from the table where he had laid them, his cuff caught the chain of Miss Carroll’s pince-nez and jerked them off. Poirot retrieved them and the gloves which he had dropped, uttering confused apologies.

‘I must apologize also once more for disturbing you,’ he ended. ‘But I fancied there might be some clue in a dispute Lord Edgware had with someone last year. Hence my questions about Paris. A forlorn hope, I fear, but Mademoiselle seemed so very positive it was not her cousin who committed the crime. Remarkably positive she was. Well, goodnight, Mademoiselle, and a thousand pardons for disturbing you.’

We had reached the door when Miss Carroll’s voice recalled us.

‘M. Poirot, these aren’t my glasses. I can’t see through them.’

‘Comment?’ Poirot stared at her in amazement. Then his face broke up into smiles. 

‘Imbecile that I am! My own glasses fell out of my pocket as I stooped to get the gloves and pick up yours. I have mixed the two pairs. They look very alike, you see.’

An exchange was made, with smiles on both sides, and we took our departure.

‘Poirot,’ I said when we were outside. ‘You don’t wear glasses.’

He beamed at me.

‘Penetrating! How quickly you see the point.’

‘Those were the pince-nez I found in Carlotta Adams’ handbag?’

‘Correct.’

‘Why did you think they might be Miss Carroll’s?’

Poirot shrugged his shoulders.

‘She is the only person connected with the case who wears glasses.’

‘However, they are not hers,’ I said thoughtfully.

‘So she affirms.’

‘You suspicious old devil.’

‘Not at all, not at all. Probably she spoke the truth. I think she did speak the truth. Otherwise I doubt if she would have noticed the substitution. I did it very adroitly, my friend.’

We were strolling through the streets more or less at random. I suggested a taxi, but Poirot shook his head.

‘I have need to think, my friend. Walking aids me.’ 

I said no more. The night was a close one and I was in no hurry to return home.

‘Were your questions about Paris mere camouflage?’ I asked curiously.

‘Not entirely.’

‘We still haven’t solved the mystery of the initial D,’ I said thoughtfully. ‘It’s odd that nobody to do with the case has an initial D – either surname or Christian name – except – oh! yes, that’s odd – except Donald Ross himself. And he’s dead.’

‘Yes,’ said Poirot in a sombre voice. ‘He is dead.’

I remembered another evening when three of us had walked at night. Remembered something else, too, and drew my breath in sharply.

‘By Jove, Poirot,’ I said. ‘Do you remember?’

‘Remember what, my friend?’

‘What Ross said about thirteen at table. And he was the first to get up. ’

Poirot did not answer. I felt a little uncomfortable as one always does when superstition is proved justified.

‘It is queer,’ I said in a low voice. ‘You must admit it is queer.’

‘Eh?’

‘I said it was queer – about Ross and thirteen. Poirot, what are you thinking about?’

To my utter amazement and, I must admit, somewhat to my disgust, Poirot began suddenly to shake with laughter. He shook and he shook. Something was evidently causing him the most exquisite mirth.

‘What the devil are you laughing at?’ I said sharply.

‘Oh! Oh! Oh!’ gasped Poirot. ‘It is nothing. It is that I think of a riddle I heard the other day. I will tell it to you. What is it that has two legs, feathers, and barks like a dog?’

‘A chicken, of course,’ I said wearily. ‘I knew that in the nursery.’

‘You are too well informed, Hastings. You should say, “I do not know.” And then me, I say, “A chicken,” and then you say, “But a chicken does not bark like a dog,” and I say, “Ah! I put that in to make it more difficult.” Supposing, Hastings, that there we have the explanation of the letter D?’