While the light lasts

'Always take a spirit-lamp about with me,' he declared. 'Most handy thing in the world. My sister's been glad enough of it this visit - not liking to worry the servants all the time you know.'

M. Poirot's eyes fell, almost apologetically as it seemed, to Mr Levering's feet, which were encased in carpet slippers.

'You have changed your boots, I see,' he murmured gently.

Levering stared at him.

'But, M. Poirot,' cried Jean, 'what are we to do?'

'There is only one thing to be done, as I said just now, Mademoiselle. Send for the police.'

'I'll go,' cried Levering. 'It won't take me a minute to put on my boots. You people had better not stay out here in the cold.'

He disappeared into the house.

'He is so thoughtful, that Mr Levering,' murmured Poirot softly. 'Shall we take his advice?'

'What about waking father and - and everybody?'

'No,' said M. Poirot sharply. 'It is quite unnecessary. Until the police come, nothing must be touched out here; so shall we go inside? To the library? I have a little history to recount to you which may distract your minds from this sad tragedy.'

He led the way, and they followed him.

'The story is about a ruby,' said M. Poirot, ensconcing himself in a comfortable arm-chair. 'A very celebrated ruby which belonged to a very celebrated man. I will not tell you his name - but he is one of the great ones of the earth. Eh bien, this great man, he arrived in London, incognito. And since, though a great man, he was also a young and a foolish man, he became entangled with a pretty young lady. The pretty young lady, she did not care much for the man, but she did care for his possessions - so much so that she disappeared one day with the historic ruby which had belonged to his house for generations. The poor young man, he was in a quandary. He is shortly to be married to a noble Princess, and he does not want the scandal. Impossible to go to the police, he comes to me, Hercule Poirot, instead. "Recover for me my ruby," he says. Eh bien, I know something of this young lady. She has a brother, and between them they have put through many a clever coup. I happen to know where they are staying for Christmas. By the kindness of Mr Endicott, whom I chance to have met, I, too, become a guest. But when this pretty young lady hears that I am arriving, she is greatly alarmed. She is intelligent, and she knows that I am after the ruby. She must hide it immediately in a safe place; and figure to yourself where she hides it - in a plum-pudding! Yes, you may well say, oh! She is stirring with the rest, you see, and she pops it into a pudding-bowl of aluminium that is different from the others. By a strange chance, that pudding came to be used on Christmas Day.'

The tragedy forgotten for the moment, they stared at him open-mouthed.

'After that,' continued the little man, 'she took to her bed.' He drew out his watch and looked at it. 'The household is astir. Mr Levering is a long time fetching the police, is he not? I fancy that his sister went with him.'

Evelyn rose with a cry, her eyes fixed on Poirot.

'And I also fancy that they will not return. Oscar Levering has been sailing close to the wind for a long time, and this is the end. He and his sister will pursue their activities abroad for a time under a different name. I alternately tempted and frightened him this morning. By casting aside all pretence he could gain possession of the ruby whilst we were in the house and he was supposed to be fetching the police. But it meant burning his boats. Still, with a case being built up against him for murder, flight seemed clearly indicated.'

'Did he kill Nancy?' whispered Jean.

Poirot rose.

'Supposing we visit once more the scene of the crime,' he suggested.

He led the way, and they followed him. But a simultaneous gasp broke from their lips as they passed outside the house. No trace of the tragedy remained; the snow was smooth and unbroken.

'Crikey!' said Eric, sinking down on the step. 'It wasn't all a dream, was it?'

'Most extraordinary,' said M. Poirot, 'The Mystery of the Disappearing Body.' His eyes twinkled gently.

Jean came up to him in sudden suspicion.

'M. Poirot, you haven't - you aren't - I say, you haven't been spoofing us all the time, have you? Oh, I do believe you have!'

'It is true, my children. I knew about your little plot, you see, and I arranged a little counterplot of my own. Ah, here is Mlle Nancy - and none the worse, I hope, after her magnificent acting of the comedy.'

It was indeed Nancy Cardell in the flesh, her eyes shining and her whole person exuberant with health and vigour.

'You have not caught cold? You drank the tisane I sent to your room?' demanded Poirot accusingly.

'I took one sip and that was enough. I'm all right. Did I do it well, M. Poirot? Oh, my arm hurts after that tourniquet!'