Poirot looked more ingenuous and childlike than ever.
"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.
"I'm going to leave you now," he announced. "I can't stand my father-in-law at any price."
Van Aldin greeted Katherine very courteously, but was clearly in a bad humour.
"You seem fond of watching tennis, M. Poirot," he growled.
"It is a pleasure to me, yes," cried Poirot placidly.
"It is as well you are in France," said Van Aldin.
"We are made of sterner stuff in the States. Business comes before pleasure there."
Poirot did not take offence; indeed, he smiled gently and confidingly at the irate millionaire.
