Yet there was something about his whole appearance that was different.
Then there was a stir of draperies behind us, and the Countess Vera Rossakoff came in.
"Ah!" said Number Four. "Our valued and trusted lieutenant.
An old friend of yours is here, my dear lady."
The countess whirled round with her usual vehemence of movement.
"God in Heaven!" she cried. "It is the little man!
Ah! but he has the nine lives of a cat!
Oh, little man, little man! Why did you mix yourself up in this?"
"Madame," said Poirot, with a bow. "Me, like the great Napoleon, I am on the side of the big battalions."
As he spoke I saw a sudden suspicion flash into her eyes, and at the same moment I knew the truth which subconsciously I already sensed.
The man beside me was not Hercule Poirot.
He was very like him, extraordinarily like him.
There was the same egg-shaped head, the same strutting figure, delicately plump.
But the voice was different, and the eyes instead of being green were dark, and surely the moustaches - those famous moustaches -?
My reflections were cut short by the countess's voice.
She stepped forward, her voice ringing with excitement.
"You have been deceived.
That man is not Hercule Poirot!"
Number Four uttered an incredulous exclamation, but the countess leant forward and snatched at Poirot's moustaches.
They came off in her hand, and then, indeed, the truth was plain.
For this man's upper lip was disfigured by a small scar which completely altered the expression of the face.
"Not Hercule Poirot," muttered Number Four. "But who can he be then?"
"I know," I cried suddenly, and then stopped dead, afraid I had ruined everything.
But the man I will still refer to as Poirot had turned to me encouragingly.
"Say it if you will.
It makes no matter now.
The trick has succeeded."
"This is Achille Poirot," I said slowly. "Hercule Poirot's twin brother."
"Impossible," said Ryland sharply, but he was shaken.
"Hercule's plan has succeeded to a marvel," said Achille placidly.
Number Four leapt forward, his voice harsh and menacing.
"Succeeded, has it?" he snarled. "Do you realise that before many minutes have passed you will be dead - dead?"
"Yes," said Achille Poirot gravely. "I realise that.
It is you who do not realise that a man may be willing to purchase success by his life.
There were men who laid down their lives for their country in the war.
I am prepared to lay down mine in the same way for the world."
It struck me just then that although perfectly willing to lay down my life I might have been consulted in the matter. Then I remembered how Poirot had urged me to stay behind, and I felt appeased.
"And in what way will your laying down your life benefit the world?" asked Ryland sardonically.
"I see that you do not perceive the true inwardness of Hercule's plan.
To begin with, your place of retreat was known some months ago, and practically all the visitors, hotel assistants and others are detectives or Secret Service men.
A cordon has been drawn round the mountain.
You may have more than one means of egress, but even so you cannot escape.
Poirot himself is directing the operations outside.
My boots were smeared with a preparation of aniseed tonight, before I came down to the terrace in my brother's place.
Hounds are following the trail.
It will lead them infallibly to the rock in the Felsenlabyrynth where the entrance is situated.
You see, do what you will to us, the net is drawn tightly round you.
You cannot escape."
Madame Olivier laughed suddenly.
"You are wrong.