'Well?' I said, puzzled.

'Mon Dieu, mon ami, but use your little grey cells? Is it not obvious? Mr. Renauld wrote his letter. Without blotting it, he re-read it carefully. Then, not on impulse, but deliberately, he added those last words, and blotted the sheet.'

'But why?'

'Parbleu! so that it should produce the effect upon me that it has upon you.'

'What?'

'But to make sure of my coming! He re-read the letter and was dissatisfied. It was not strong enough!'

He paused, and then added softly, his eyes shining with that green light that always betokened inward excitement:

'And so, mon ami, since that postscript was added, not on impulse, but soberly, in cold blood, the urgency is very great, and we must reach him as soon as possible.'

'Merlinville,' I murmured thoughtfully. 'I've heard of it, I think.'

Poirot nodded.

'It is a quiet little place-but chic! It lies about midway between Boulogne and Calais. Mr. Renauld has a house in England, I suppose?'

'Yes, in Rutland Gate, as far as I remember. Also a big place in the country, somewhere in Hertfordshire. But I really know very little about him, he doesn't do much in a social way. I believe he has large South American interests in the City, and has spent most of his life out in Chile and the Argentine.'

'Well, we shall hear all details from the man himself. Come, let us pack. A small suitcase each, and then a taxi to Victoria.'

Eleven o'clock saw our departure from Victoria on our way to Dover. Before starting Poirot had dispatched a telegram to Mr. Renauld giving the time of our arrival at Calais.

On the boat, I knew better than to disturb my friend's solitude. The weather was gorgeous, and the sea as smooth as the proverbial millpond so I was hardly surprised when a smiling Poirot joined me on disembarking at Calais. A disappointment was in store for us, as no car had been sent to meet us, but Poirot put this down to his telegram having been delayed in transit.