"But you distrust the obvious, eh?" said our visitor, smiling.

"Go on, Poirot," I urged.

"It will be your responsibility, mon ami."

As he lifted the receiver, the man made a sudden, catlike jump at me. I was ready for him. In another minute we were locked together, staggering round the room.

Suddenly I felt him slip and falter. I pressed my advantage. He went down before me. And then, in the very flush of victory, an extraordinary thing happened.

I felt myself flying forwards. Head first, I crashed into the wall in a complicated heap. I was up in a minute, but the door was already closing behind my late adversary. I rushed to it and shook it, it was locked on the outside. I seized the telephone from Poirot.

"Is that the bureau? Stop a man who is coming out. A tall man, with a buttoned-up overcoat and a soft hat. He is wanted by the police."

Very few minutes elapsed before we heard a noise in the corridor outside. The key was turned and the door flung open. The manager himself stood in the doorway.

"The man-you have got him?" I cried.

"No, monsieur. No one has descended."

"You must have passed him."

"We have passed no one, monsieur. It is incredible that he can have escaped."

"You have passed some one, I think," said Poirot, in his gentle voice. "One of the hotel staff, perhaps?"

"Only a waiter carrying a tray, monsieur."

"Ah!" said Poirot, in a tone that spoke infinities.

"So that was why he wore his overcoat buttoned up to his chin," mused Poirot, when we had finally got rid of the excited hotel officials.

"I'm awfully sorry, Poirot," I murmured, rather crestfallen. "I thought I'd downed him all right."

"Yes, that was a Japanese trick, I fancy. Do not distress yourself, mon ami. All went according to plan-his plan. That is what I wanted."

"What's this?" I cried, pouncing on a brown object that lay on the floor.

It was a slim pocket-book of brown leather, and had evidently fallen from our visitor's pocket during his struggle with me. It contained two receipted bills in the name of M. Felix Laon, and a folded-up piece of paper which made my heart beat faster. It was a half sheet of note-paper on which a few words were scrawled in pencil but they were words of supreme importance.

"The next meeting of the council will be on Friday at 34 Rue des Echelles at 11 a.m."

It was signed with a big figure 4.

And to-day was Friday, and the clock on the mantelpiece showed the hour to be 10.30. 

"My God, what a chance!" I cried. "Fate is playing into our hands. We must start at once-though. What stupendous luck."

"So that was why he came," murmured Poirot. "I see it all now."

"See what? Come on, Poirot, don't stay daydreaming there."

Poirot looked at me, and slowly shook his head, smiling as he did so.

" 'Will you walk into my parlour, said the spider to the fly?' That is your little English nursery rhyme, is it not? No, no-they are subtle-but not so subtle as Hercule Poirot."

"What on earth are you driving at, Poirot?"

"My friend, I have been asking myself the reason of this morning's visit. Did our visitor really hope to succeed in bribing me? Or, alternatively, in frightening me into abandoning my task? It seemed hardly credible.

Why, then, did he come? And now I see the whole plan -very neat-very pretty-the ostensible reason to bribe or frighten me-the necessary struggle which he took no pains to avoid, and which should make the dropped pocket-book natural and reasonable-and finally-the pitfall! Rue des Eschelles, 11 a.m.? I think not, mon ami\ One does not catch Hercule Poirot as easily as that."

"Good heavens," I gasped.

Poirot was frowning to himself.

"There is still one thing I do not understand."

"What is that?"

"The time, Hastings-the time. If they wanted to decoy me away, surely night time would be better? Why this early hour? Is it possible that something is about to happen this morning? Something which they are anxious Hercule Poirot should not know about?"

He shook his head.

"We shall see. Here I sit, mon ami. We do not stir out this morning. We await events here."

It was at half-past eleven exactly that the summons came. A. petit bleu. Poirot tore it open, then handed it to me. It was from Madame Olivier, the world-famous scientist, whom we had visited yesterday in connection with the Halliday case. It asked us to come out to Passy at once.

We obeyed the summons without an instant's delay.

Madame Olivier received us in the same small salon. I was struck anew with the wonderful power of this woman, with her long nun's face and burning eyes-this brilliant successor of Becquerel and the Curies. She came to the point at once.

"Messieurs, you interviewed me yesterday about the disappearance of M. Halliday. I now learn that you returned to the house a second time, and asked to see my secretary, Inez Veroneau. She left the house with you, and has not returned here since."

"Is that all, madame?"

"No, monsieur, it is not. Last night the laboratory was broken into, and several valuable papers and memoranda were stolen. The thieves had a try for something more precious still, but luckily they failed to open the big safe."

"Madame, these are the facts of the case. Your late secretary, Madame Veroneau, was really the Countess Rossakoff, an expert thief, and it was she who was responsible for the disappearance of M. Halliday. How long had she been with you?"

"Five months, monsieur. What you say amazes me."

"It is true, nevertheless. These papers, were they easy to find? Or do you think an inside knowledge was shown?"

"It is rather curious that the thieves knew exactly where to look. You think Inez-"

"Yes, I have no doubt that it was upon her information that they acted. But what is this precious thing that the thieves failed to find? Jewels?"

Madame Olivier shook her head with a faint smile.

"Something much more precious than that, monsieur."

She looked round her, then bent forward, lowering her voice. "Radium, monsieur."

"Radium?"

"Yes, monsieur. I am now at the crux of my experiments.

I possess a small portion of radium myself-more has been lent to me for the process I am at work upon. Small though the actual quantity is, it comprises a large amount of the world's stock and represents a value of millions of francs."

"And where is it?"

"In its leaden case in the big safe-the safe purposely appears to be of an old and worn-out pattern, but it is really a triumph of the safe-makers' art. That is probably why the thieves were unable to open it."

"How long are you keeping this radium in your possession?"

"Only for two days more, monsieur. Then my experiments will be concluded."

Poirot's eyes brightened.

"And Inez Veroneau is aware of the fact? Good- then our friends will come back. Not a word of me to any one, madame. But rest assured, I will save your radium for you. You have a key of the door leading from the laboratory to the garden?"

"Yes, monsieur. Here it is. I have a duplicate for myself. And here is the key of the garden door leading out into the alleyway between this villa and the next one."

"I thank you, madame. To-night, go to bed as usual, have no fears, and leave all to me. But not a word to any one-not to your two assistants-Mademoiselle Claude and Monsieur Henri, is it not?-particularly not a word to them."

Poirot left the villa rubbing his hands in great satisfaction.

"What are we going to do now?" I asked.

"Now, Hastings, we are about to leave Paris-for England."

"What?"

"We will pack our effects, have lunch, and drive to theGareduNord."

"But the radium?"

"I said we were going to leave for England-I did not say we were going to arrive there. Reflect a moment, Hastings. It is quite certain that we are being watched and followed. Our enemies must believe that we are going back to England, and they certainly will not believe that unless they see us get on board the train and start."