There was the usual long screaming sigh of the brake, and the train slackened speed and drew into Lyons. Van Aldin let down the window and leant out.

“If it wasn’t Derek⁠—if your new theory is correct, it is here that the man left the train?” he asked over his shoulder.

Rather to his surprise Poirot shook his head.

“No,” he said thoughtfully, “no man left the train, but I think⁠—yes, I think, a woman may have done so.”

Knighton gave a gasp.

“A woman?” demanded Van Aldin sharply.