Poirot moved towards the door. I followed him.
“There is one more thing that you have failed to take into account,” he said over his shoulder.
“What is that?”
“The piece of lead piping,” said Poirot, and left the room.
Jack Renauld still stood in the hall, with a white dumb face, but as we came out of the salon, he looked up sharply. At the same moment there was the sound of a footfall on the staircase. Mrs. Renauld was descending it. At the sight of her son, standing between the two myrmidons of the law, she stopped as though petrified.
“Jack,” she faltered. “Jack, what is this?”
He looked up at her, his face set.
“They have arrested me, mother.”
“What?”
She uttered a piercing cry, and before any one could get to her swayed and fell heavily. We both ran to her and lifted her up. In a minute Poirot stood up again.