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.