“But you distrust the obvious, eh?” said our visitor, smiling.

“Go on, Poirot,” I urged.

“It will be your responsibility, mon ami .”

As he lifted the receiver, the man made a sudden, catlike jump at me. I was ready for him. In another minute we were locked together, staggering round the room. Suddenly I felt him slip and falter. I pressed my advantage. He went down before me. And then, in the very flush of victory, an extraordinary thing happened. I felt myself flying forwards. Headfirst, I crashed into the wall in a complicated heap. I was up in a minute, but the door was already closing behind my late adversary. I rushed to it and shook it, it was locked on the outside. I seized the telephone from Poirot.

“Is that the bureau? Stop a man who is coming out. A tall man, with a buttoned-up overcoat and a soft hat. He is wanted by the police.”