“Good evening, Monsieur. Your compartment is the No. 1.”

He called to the porters and they wheeled their load halfway along the carriage on which the tin plates proclaimed its destination:

“You are full up to-night, I hear?”

“It is incredible, Monsieur. All the world elects to travel to-night!”

“All the same you must find room for this gentleman here. He is a friend of mine. He can have the No. 16.”

“It is taken, Monsieur.”

“What? The No. 16?”

A glance of understanding passed between them, and the conductor smiled. He was a tall sallow man of middle age.

“But yes, Monsieur. As I told you, we are full-full-everywhere.”

“But what passes itself?” demanded M. Bouc angrily. “There is a conference somewhere? It is a party?”

“No, Monsieur. It is only chance. It just happens that many people have elected to travel to-night.”

M. Bouc made a clicking sound of annoyance.

“At Belgrade,” he said, “there will be the slip coach from Athens. There will also be the Bucharest-Paris coach. But we do not reach Belgrade until to-morrow evening. The problem is for to-night. There is no second-class berth free?”

“There is a second-class berth, Monsieur-”

“Well, then-”

“But it is a lady’s berth. there is already a German woman in the compartment-a lady’s maid.”

“La- la, that is awkward,” said M. Bouc.

“Do not distress yourself, my friend,” said Poirot. “I must travel in an ordinary carriage.”

“Not at all. Not at all.” He turned once more to the conductor. “Everyone has arrived?”

“It is true,” said the man, “that there is one passenger who has not yet arrived.” He spoke slowly, with hesitation.

“But speak then!”

“No. 7 berth-a second-class. The gentleman has not yet come, and it is four minutes to nine.”

“Who is it?”