'But yes, my friend, it is against all my instincts so to ruin my appearance, but what will you?'

'But Lavington can't have buried it under the coal?'

'If you would use your eyes, you would see that it is not the coal that I examine.'

I then saw that on a shelf behind the coal-bunker some logs of wood were piled. Poirot was dexterously taking them down one by one. Suddenly he uttered a low exclamation.

'Your knife, Hastings!'

I handed it to him. He appeared to insert it in the wood, and suddenly the log split in two. It had been neatly sawn in half and a cavity hollowed out in the centre. From this cavity Poirot took a little wooden box of Chinese make.

'Well done!' I cried, carried out of myself.

'Gently, Hastings! Do not raise your voice too much. Come, let us be off, before the daylight is upon us.'

Slipping the box into his pocket, he leaped lightly out of the coal-bunker, brushed himself down as well as he could, and leaving the house by the same way as we had come, we walked rapidly in the direction of London.

'But what an extraordinary place!' I expostulated. 'Anyone might have used the log.'

'In July, Hastings? And it was at the bottom of the pile - a very ingenious hiding-place. Ah, here is a taxi! Now for home, a wash, and a refreshing sleep.'

After the excitement of the night, I slept late. When I finally strolled into our sitting-room just before one o'clock, I was surprised to see Poirot, leaning back in an armchair, the Chinese box open beside him, calmly reading the letter he had taken from it.

He smiled at me affectionately, and tapped the sheet he held.

'She was right, the Lady Millicent; never would the Duke have pardoned this letter! It contains some of the most extravagant terms of affection I have ever come across.'

'Really, Poirot,' I said, rather disgustedly, 'I don't think you should really have read the letter. That's the sort of thing that isn't done.'

'It is done by Hercule Poirot,' replied my friend imperturbably.

'And another thing,' I said. 'I don't think using Japp's official card yesterday was quite playing the game.'

'But I was not playing a game, Hastings. I was conducting a case.'

I shrugged my shoulders. One can't argue with a point of view.

'A step on the stairs,' said Poirot. 'That will be Lady Millicent.'

Our fair client came in with an anxious expression on her face which changed to one of delight on seeing the letter and box which Poirot held up.

'Oh, M. Poirot. How wonderful of you! How did you do it?'

'By rather reprehensible methods, milady. But Mr Lavington will not prosecute. This is your letter, is it not?'

She glanced through it.

'Yes. Oh, how can I ever thank you! You are a wonderful, wonderful man. Where was it hidden?'

Poirot told her.

'How very clever of you!' She took up the small box from the table. 'I shall keep this as a souvenir.'