‘Can you tell me anything about her?’ I asked.

‘Anything about her?’

‘Yes, where she comes from, who her people are – that sort of thing?’

Mrs Folliott’s face wore more than ever its frozen look.

‘I don’t know at all.’

‘Who was she with before she came to you?’

‘I’m afraid I don’t remember.’

There was a spark of anger now underlying her nervousness. She flung up her head in a gesture that was vaguely familiar.

‘Is it really necessary to ask all these questions?’

‘Not at all,’ I said, with an air of surprise and a tinge of apology in my manner. ‘I had no idea you would mind answering them. I am very sorry.’

Her anger left her and she became confused again.

‘oh! I don’t mind answering them. I assure you I don’t. Why should I? It – it just seemed a little odd, you know. That’s all. A little odd.’

One advantage of being a medical practitioner is that you can usually tell when people are lying to you. I should have known from Mrs Folliott’s manner, if from nothing else, that she did mind answering my questions – minded intensely. She was thoroughly uncomfortable and upset, and there was plainly some mystery in the background. I judged her to be a woman quite unused to deception of any kind, and consequently rendered acutely uneasy when forced to practise it. A child could have seen through her.

But it was also clear the she had no intention of telling me anything further. Whatever the mystery centring round Ursula Bourne might be, I was not going to learn it through Mrs Folliott.

Defeated, I apologized once more for disturbing her, took my hat and departed.

I went to see a couple of patients and arrived home about six o’clock. Caroline was sitting beside the wreck of tea things. She had that look of suppressed exultation on her face which I know only too well. It is a sure sign with her of either the getting or the giving of information. I wondered which it had been.

‘I’ve had a very interesting afternoon,’ began Caroline, as I dropped into my own particular easy-chair and stretched out my feet to the inviting blaze in the fireplace.

‘Have you?’ I said. ‘Miss Gannett drop in to tea?’

Miss Gannett is one of the chief of our news-mongers.

‘Guess again,’ said Caroline, with intense complacency.

I guessed several times, working slowly through all the members of Caroline’s Intelligence corps. My sister received each guess with a triumphant shake of the head. In the end she volunteered the information herself.

‘M. Poirot!’ she said. ‘Now, what do you think of that?’

I thought a good many things of it, but I was careful not to say them to Caroline.

‘Why did he come?’ I asked.

‘To see me, of course. He said that, knowing my brother so well, he hoped he might be permitted to make the acquaintance of his charming sister – your charming sister, I’ve got mixed up – but you know what I mean.’

‘What did he talk about?’ I asked.

‘He told me a lot about himself and his cases. You know that Prince Paul of Mauretania – the one who’s just married a dancer?’

‘Yes?’

‘I saw a most intriguing paragraph about her in Society Snippets the other day, hinting that she was really a russian grand duchess – one of the czar’s daughters who managed to escape from the Bolsheviks. Well, it seems that M. Poirot solved a baffling murder mystery that threatened to involve them both. Prince Paul was beside himself with gratitude.’

‘Did he give him an emerald tie pin the size of a plover’s egg?’ I inquired sarcastically.

‘He didn’t mention it. Why?’

‘Nothing,’ I said. ‘I thought it was always done. It is in detective fiction anyway. The super-detective always has his rooms littered with rubies and pearls and emeralds from grateful royal clients.’