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.