"Ring the bell, I pray of you, Hastings. Three times, for the valet." I obeyed, devoured with curiosity. Meanwhile Poirot had emptied the waste-paper basket on the floor, and was swiftly going through its contents.

In a few moments the valet answered the bell. To him Poirot put the same question, and handed him the card to examine. But the response was the same. The valet had never seen a card of that particular quality among Mr Opalsen's belongings. Poirot thanked him, and he withdrew, somewhat unwillingly, with an inquisitive glance at the overturned waste-paper basket and the litter on the floor. He could hardly have helped over-hearing Poirot's thoughtful remark as he bundled the torn papers back again:

"And the necklace was heavily insured..."

"Poirot," I cried, "I see -"

"You see nothing, my friend," he replied quickly. "As usual, nothing at all! It is incredible - but there it is. Let us return to our own apartments."

We did so in silence. Once there, to my intense surprise, Poirot effected a rapid change of clothing.

"I go to London tonight," he explained. "It is imperative."

"What?"

"Absolutely. The real work, that of the brain (ah, those brave little gray cells), it is done. I go to seek the confirmation. I shall find it! Impossible to deceive Hercule Poirot!"

"You'll come a cropper one of these days," I observed, rather disgusted by his vanity.

"Do not be enraged, I beg of you, mon ami. I count on you to do me a service - of your friendship."

"Of course," I said eagerly, rather ashamed of my moroseness. "What is it?"

"The sleeve of my coat that I have taken off - will you brush it? See you, a little white powder has clung to it. You without doubt observed me run my finger round the drawer of the dressing-table?"

"No, I didn't."

"You should observe my actions, my friend. Thus I obtained the powder on my finger, and, being a little over-excited, I rubbed it on my sleeve; an action without method which I deplore - false to all my principles."

"But what was the powder?" I asked, not particularly interested in Poirot's principles.

"Not the poison of the Borgias," replied Poirot, with a twinkle. "I see your imagination mounting. I should say it was French chalk."

"French chalk?"

"Yes, cabinet-makers use it to make drawers run smoothly."

I laughed.

"You old sinner! I thought you were working up to something exciting."

"Au revoir, my friend. I save myself. I fly!"

The door shut behind him. With a smile, half of derision, half of affection, I picked up the coat, and stretched out my hand for the clothes brush.

The next morning, hearing nothing from Poirot, I went out for a stroll, met some old friends, and lunched with them at their hotel. In the afternoon we went for a spin. A punctured tire delayed us, and it was past eight when I got back to the Grand Metropolitan.