These reassurances were all very well, I thought, as Poirot gallantly ushered his fair client down the stairs, but it seemed to me that we had a tough nut to crack. I said as much to Poirot when he returned. He nodded ruefully.

'Yes - the solution does not leap to the eye. He has the whip hand, this M. Lavington. For the moment I do not see how we are to circumvent him.'

Mr Lavington duly called upon us that afternoon. Lady Millicent had spoken truly when she described him as an odious man. I felt a positive tingling in the end of my boot, so keen was I to kick him down the stairs. He was blustering and overbearing in manner, laughed Poirot's gentle suggestions to scorn, and generally showed himself as master of the situation. I could not help feeling that Poirot was hardly appearing at his best. He looked discouraged and crestfallen.

'Well, gentlemen,' said Lavington, as he took up his hat, 'we don't seem to be getting much further. The case stands like this: I'll let the Lady Millicent off cheap, as she is such a charming young lady.'

He leered odiously. 'We'll say eighteen thousand. I'm off to Paris today - a little piece of business to attend to over there. I shall be back on Tuesday. Unless the money is paid by Tuesday evening, the letter goes to the Duke. Don't tell me Lady Millicent can't raise the money. Some of her gentlemen friends would be only too willing to oblige such a pretty woman with a loan - if she goes the right way about it.'

My face flushed, and I took a step forward, but Lavington had wheeled out of the room as he finished his sentence.

'My God!' I cried. 'Something has got to be done. You seem to be taking this lying down, Poirot.'

'You have an excellent heart, my friend - but your grey cells are in a deplorable condition. I have no wish to impress Mr Lavington with my capabilities. The more pusillanimous he thinks me, the better.'

'Why?'

'It is curious,' murmured Poirot reminiscently, 'that I should have uttered a wish to work against the law just before Lady Millicent arrived!'

'You are going to burgle his house while he is away?' I gasped.

'Sometimes, Hastings, your mental processes are amazingly quick.'

'Suppose he takes the letter with him?'

Poirot shook his head.

'That is very unlikely. He has evidently a hiding-place in his house that he fancies to be pretty impregnable.'

'When do we - er - do the deed?'

'Tomorrow night. We will start from here about eleven o'clock.'

At the time appointed I was ready to set off. I had donned a dark suit, and a soft dark hat. Poirot beamed kindly on me.

'You have dressed the part, I see,' he observed. 'Come let us take the underground to Wimbledon.'

'Aren't we going to take anything with us? Tools to break in with?'