Knighton yawned.

"Of all the darned uncomfortable journeys," he murmured. "I suppose you know what you are playing at, Monsieur Poirot."

He composed himself to sleep as best he could. Both he and Van Aldin had succumbed to slumber, when Poirot, glancing for the fourteenth time at his watch, leant across and tapped the millionaire on the shoulder.

"Eh? What is it?"

"In five or ten minutes, Monsieur, we shall arrive at Lyons."

"My God!" Van Aldin's face looked white and haggard in the dim light. "Then it must have been about this time that poor Ruth was killed."

He sat staring straight in front of him. His lips twitched a little, his mind reverting back to the terrible tragedy that had saddened his life.

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.