“Ah!⁠—before I forget it.” He whipped something from a pocket and held it out.

“Permit me to offer you a cigarette⁠—out of your own cigarette-case. It was careless of you to drop it when you boarded the train on the ceinture at Paris.”

Knighton stood staring at him as though stupefied. Then he made a movement, but Poirot flung up his hand in a warning gesture.

“No, don’t move,” he said in a silky voice; “the door into the next compartment is open, and you are being covered from there this minute. I unbolted the door into the corridor when we left Paris, and our friends the police were told to take their places there. As I expect you know, the French police want you rather urgently, Major Knighton⁠—or shall we say⁠—Monsieur le Marquis?”