"I was right.
See you, I was right.
Impossible to deceive Hercule Poirot!"
He rushed to the telephone - waited impatiently.
"Is that Japp?
Ah!
Japp, it is you. Hercule Poirot speaks.
Watch the man-servant, Ivan.
On no account let him slip through your fingers.
Yes, yes, it is as I say."
He dashed down the receiver and turned to me.
"You see it not, Hastings?
I will explain.
Wilson was not poisoned, he was electrocuted.
A thin metal rod passes up the middle of one of those chessmen.
The table was prepared beforehand and set upon a certain spot on the floor.
When the bishop was placed upon one of the silver squares, the current passed through Wilson's body, killing him instantly.
The only mark was the electric burn upon his hand - his left hand, because he was left-handed.
The 'special table' was an extremely cunning piece of mechanism.
The table I examined was a duplicate, perfectly innocent.
It was substituted for the other immediately after the murder.
The thing was worked from the flat below, which, if you remember, was let furnished.
But one accomplice at least was in Savaronoff's flat.
The girl is an agent of the Big Four, working to inherit Savaronoff's money."
"And Ivan?"
"I strongly suspect that Ivan is none other than the famous Number Four."
"What?"
"Yes.
The man is a marvellous character actor.
He can assume any part he pleases."
I thought back over past adventures, the lunatic asylum keeper, the butcher's young man, the suave doctor, all the same man, and all totally unlike each other.
"It's amazing," I said at last. "Everything fits in.
Savaronoff had an inkling of the plot, and that's why he was so averse to playing the match."
Poirot looked at me without speaking.
Then he turned abruptly away, and began pacing up and down.
"Have you a book on chess by any chance, mon ami?" he asked suddenly.
"I believe I have somewhere."
It took me some time to ferret it out, but I found it at last, and brought it to Poirot, who sank down in a chair and started reading it with the greatest attention.
In about a quarter of an hour the telephone rang.
I answered it.
It was Japp.
Ivan had left the flat, carrying a large bundle.
He had sprung into a waiting taxi, and the chase had begun.
He was evidently trying to lose his pursuers.
In the end he seemed to fancy that he had done so, and had then driven to a big empty house at Hampstead.
The house was surrounded.
I recounted all this to Poirot.
He merely stared at me as though he scarcely took in what I was saying.
He held out the chess book.
"Listen to this, my friend. This is the Ruy Lopez opening.