"A chessman!" he exclaimed. "A white bishop. Was that in his pocket?"

"No, clasped in his hand. We had quite a difficulty to get it out of his fingers. It must be returned to Dr.

Savaronoff sometime. It's part of a very beautiful set of carved ivory chessmen."

"Permit me to return it to him. It will make an excuse for my going there."

"Aha!" cried Japp. "So you want to come in on this case?"

"I admit it. So skilfully have you aroused my interest."

"That's fine. Got you away from your brooding.

Captain Hastings is pleased, too, I can see."

"Quite right," I said, laughing.

Poirot turned back towards the body.

"No other little detail you can tell me about-him?" he asked.

"I don't think so."

"Not even-that he was left-handed?"

"You're a wizard, Moosior Poirot. How did you know that? He was left-handed. Not that it's anything to do with the case."

"Nothing whatever," agreed Poirot hastily, seeing that Japp was slightly ruffled. "My little joke-that was all. I like to play you the trick, see you."

We went out upon an amicable understanding.

The following morning saw us wending our way to Dr. Savaronoff's flat in Westminster.

"Sonia Daviloff," I mused. "It's a pretty name."

Poirot stopped, and threw me a look of despair.

"Always looking for romance! You are incorrigible.

It would serve you right if Sonia Daviloff turned out to be our friend and enemy the Countess Vera Rossakoff."

At the mention of the countess, my face clouded over.

"Surely, Poirot, you don't suspect-"

"But, no, no. It was a joke! I have not the Big Four on the brain to that extent, whatever Japp may say."

The door of the flat was opened to us by a man-servant with a peculiarly wooden face. It seemed impossible to believe that that impassive countenance could ever display emotion.

Poirot presented a card on which Japp had scribbled a few words of introduction, and we were shown into a low, long room furnished with rich hangings and curios.

One or two wonderful ikons hung upon the walls, and exquisite Persian rugs lay upon the floor. A samovar stood upon a table.

I was examining one of the ikons which I judged to be of considerable value, and turned to see Poirot prone upon the floor. Beautiful as the rug was, it hardly seemed to be to necessitate such close attention.

"Is it such a very wonderful specimen?" I asked.

"Eh? Oh! the rug? But no, it was not the rug I was remarking. But it is a beautiful specimen, far too beautiful to have a large nail wantonly driven through the middle of it. No, Hastings," as I came forward, "the nail is not there now. But the hole remains."

A sudden sound behind us made me spin round, and Poirot spring nimbly to his feet. A girl was standing in the doorway. Her eyes, fell upon us, were dark with suspicion. She was of medium height, with a beautiful, rather sullen face, dark blue eyes, and very black hair which was cut short. Her voice, when she spoke, was rich and sonorous, and completely un-English.

"I fear my uncle will be unable to see you. He is a great invalid."

"That is a pity, but perhaps you will kindly help me instead. You are Mademoiselle Daviloff, are you not?" 

"Yes, I am Sonia Daviloff. What is it you want to know?"

"I am making some inquiries about that sad affair the night before last-the death of M. Gilmour Wilson.

What can you tell me about it?"

The girl's eyes opened wide.

"He died of heart failure-as he was playing chess."

"The police are not so sure that it was-heart failure, mademoiselle."

The girl gave a terrified gesture.

"It was true then," she cried. "Ivan was right."

"Who is Ivan, and why do you say he was right?"

"It was Ivan who opened the door to you-and he has already said to me that in his opinion Gilmour Wilson did not die a natural death-that he was poisoned by mistake."

"By mistake."

"Yes, the poison was meant for my uncle."

She had quite forgotten her first distrust now, and was speaking eagerly.

"Why do you say that, mademoiselle. Who should wish to poison Dr. Savaronoff?"

She shook her head.

"I do not know. I am all in the dark. And my uncle, he will not trust me. It is natural, perhaps. You see, he hardly knows me. He saw me as a child, and not since till I came to live with him here in London. But this much I do know, he is in fear of something. We have many secret societies in Russia, and one day I overheard something which made me think it was of just such a society he went in fear. Tell me, monsieur"-she came a step nearer, and dropped her voice-"have you ever heard of a society called the 'Big Four'?"

Poirot jumped nearly out of his skin. His eyes positively bulged with astonishment.

"Why do you-what do you know of the Big Four, mademoiselle?"

"There is such an association, then! I overheard a reference to them, and asked my uncle about it afterwards.

Never have I seen a man so afraid. He turned all white and shaking. He was in fear of them, monsieur, in great fear, I am sure of it. And, by mistake, they killed the American, Wilson."

"The Big Four," murmured Poirot. "Always the Big Four! An astonishing coincidence, mademoiselle, your uncle is still in danger. I must save him. Now recount to me exactly the events of that fatal evening. Show me the chess-board, the table, how the two men sat-everything."

She went to the side of the room and brought out a small table. The top of it was exquisite, inlaid with squares of silver and black to represent a chessboard.

"This was sent to my uncle a few weeks ago as a present, with the request that he would use it in the next match he played. It was in the middle of the room-so."

Poirot examined the table with what seemed to me quite unnecessary attention. He was not conducting the inquiry at all as I would have done. Many of his questions seemed to me pointless, and upon really vital matters he seemed to have no questions to ask. I concluded that the unexpected mention of the Big Four had thrown him completely off his balance.

After a minute examination of the table and the exact position it had occupied, he asked to see the chessmen.

Sonia Daviloff brought them to him in a box. He examined one or two of them in a perfunctory manner.

"An exquisite set," he murmured absentmindedly. 

Still not a question as to what refreshments there had been, or what people had been present.

I cleared my throat significantly.

"Don't you think, Poirot, that-"

He interrupted me peremptorily.

"Do not think, my friend. Leave all to me. Mademoiselle, is it quite impossible that I should see your uncle?"

A faint smile showed itself on her face.

"He will see you, yes. You understand, it is my part to interview all strangers first."

She disappeared. I heard a murmur of voices in the next room, and a minute later she came back and motioned us to pass into the adjoining room.

The man who lay there on a couch was an imposing figure. Tall, gaunt, with huge bushy eyebrows and white beard, and a face haggard as the result of starvation and hardships. Dr. Savaronoff was a distinct personality. I noted the peculiar formation of his head, its unusual height. A great chess player must have a great brain, I knew. I could easily understand Dr. Savaronoff being the second greatest player in the world.

Poirot bowed.

"M. Ie Docteur, may I speak to you alone?"

Savaronoff turned to his niece.

"Leave us, Sonia."

She disappeared obediently.

"Now, sir, what is it?"

"Dr. Savaronoff, you have recently come into an enormous fortune. If you should-die unexpectedly, who inherits it?"

"I have made a will leaving everything to my niece, Sonia Daviloff. You do not suggest-"

"I suggest nothing, but you have not seen your niece since she was a child. It would have been easy for any one to impersonate her."