"I don't think so," one of them said; "I should certainly have noticed that Scotch rug; but I did not see it."
"Then there was a fourth passenger in this compartment?" the official enquired.
"No, we travelled alone," said one of the men, but the other dissented.
"It is very odd, and I am not sure about it, but I really am wondering whether someone did not get into our compartment last night while we were asleep. I have a vague impression that someone did, but I can't be sure."
"Do try to remember, sir," the official urged him; "it is of the very highest importance."
But the passenger shook his shoulders doubtfully.
"No, I really can't say anything definite; and, besides, I have a shocking headache."
The official was silent for a minute or two.
"In my opinion, gentlemen, you have been uncommonly lucky to escape murder yourselves. I do not quite understand yet how the murder was done, but I incline to think it proves almost incredible daring. However——" He stopped and put his head out of the window. "You can send the train on now," he called to a porter, and resumed: "However, I must ask you to accompany me to the stationmaster's office and give me your names and addresses, and to help me afterwards in the conduct of the legal investigation."
The two travellers looked at one another in distressed surprise.