‘The case of Felicie Bault was investigated by lawyers as well as by doctors and scientists,’ said Dr Campbell Clark quickly. ‘Maître Quimbellier, you remember, made the most thorough investigation and confirmed the views of the scientists. And after all, why should it surprise us so much? We come across the double-yolked egg, do we not? And the twin banana? Why not the double soul—or in this case the quadruple soul—in the single body?’

‘The double soul?’ protested the Canon.

Dr Campbell Clark turned his piercing blue eyes on him.

‘What else can we call it? That is to say—if the personality is the soul?’

‘It is a good thing such a state of affairs is only in the nature of a “freak”,’ remarked Sir George. ‘If the case were common, it would give rise to pretty complications.’

‘The condition is, of course, quite abnormal,’ agreed the doctor. ‘It was a great pity that a longer study could not have been made, but all that was put an end to by Felicie’s unexpected death.’

‘There was something queer about that, if I remember rightly,’ said the lawyer slowly.

Dr Campbell Clark nodded.

‘A most unaccountable business. The girl was found one morning dead in bed. She had clearly been strangled. But to everyone’s stupefaction it was presently proved beyond doubt that she had actually strangled herself. The marks on her neck were those of her own fingers. A method of suicide which, though not physically impossible, must have necessitated terrific muscular strength and almost superhuman will power. What had driven the girl to such straits has never been found out. Of course her mental balance must always have been precarious. Still, there it is. The curtain has been rung down for ever on the mystery of Felicie Bault.’

It was then that the man in the far corner laughed.

The other three men jumped as though shot. They had totally forgotten the existence of the fourth amongst them. As they stared towards the place where he sat, still huddled in his overcoat, he laughed again.

‘You must excuse me, gentlemen,’ he said, in perfect English that had, nevertheless, a foreign flavour.

He sat up, displaying a pale face with a small jet-black moustache.

‘Yes, you must excuse me,’ he said, with a mock bow. ‘But really! in science, is the last word ever said?’

‘You know something of the case we have been discussing?’ asked the doctor courteously.

‘Of the case? No. But I knew her.’

‘Felicie Bault?’

‘Yes. And Annette Ravel also. You have not heard of Annette Ravel, I see? And yet the story of the one is the story of the other. Believe me, you know nothing of Felicie Bault if you do not also know the history of Annette Ravel.’

He drew out his watch and looked at it.

‘Just half an hour before the next stop. I have time to tell you the story—that is, if you care to hear it?’

‘Please tell it to us,’ said the doctor quietly.