“I thought perhaps you might have dropped it when you were in your wife’s compartment,” he explained guilelessly.

“I never was there. I have already told the police that a dozen times.”

“A thousand pardons,” said Poirot, with his most apologetic air. “It was Mademoiselle here who mentioned having seen you going in.”

He stopped with an air of embarrassment.

Katherine looked at Derek. His face had gone rather white, but perhaps that was her fancy. His laugh, when it came, was natural enough.

“You made a mistake, Miss Grey,” he said easily. “From what the police have told me, I gather that my own compartment was only a door or two away from that of my wife’s⁠—though I never suspected the fact at the time. You must have seen me going into my own compartment.” He got up quickly as he saw Van Aldin and Knighton approaching.