“Highly irregular,” said Colonel Arbuthnot coldly.

“Not so. You see, this crime, it was most probably committed by a woman. The man was stabbed no fewer than twelve times. Even the chef de train said at once, ‘It is a woman.’ Well, then, what is my first task? To give all the women travelling on the Istanbul-Calais coach what Americans call the ‘once-over.’ But to judge of an Englishwoman is difficult. They are very reserved, the English. So I appeal to you, Monsieur, in the interest of justice. What sort of person is this Miss Debenham? What do you know about her?”

“Miss Debenham,” said the Colonel with some warmth, “is a lady.”

“Ah!” said Poirot with every appearance of being much gratified. “So you do not think that she is likely to be implicated in this crime?”

“The idea is absurd,” said Arbuthnot. “The man was a perfect stranger – she had never seen him before.”

“Did she tell you so?”

“She did. She commented at once upon his somewhat unpleasant appearance. If a woman is concerned, as you seem to think (to my mind without any evidence but on a mere assumption), I can assure you that Miss Debenham could not possibly be implicated.”

“You feel warmly in the matter,” said Poirot with a smile.

Colonel Arbuthnot gave him a cold stare. “I really don’t know what you mean,” he said.

The stare seemed to abash Poirot. He dropped his eyes and began fiddling with the papers in front of him.

“All this is by the way,” he said. “Let us be practical and come to facts. This crime, we have reason to believe, took place at a quarter past one last night. It is part of the necessary routine to ask everyone on the train what he or she was doing at that time.”

“Quite so. At a quarter past one, to the best of my belief, I was talking to the young American fellow-secretary to the dead man.”

“Ah! were you in his compartment, or was he in yours?”

“I was in his.”

“That is the young man of the name of MacQueen?”

“Yes.”

“He was a friend or acquaintance of yours?”

“No, I never saw him before this journey. We fell into casual conversation yesterday and both became interested. I don’t as a rule like Americans – haven’t any use for ’em–”

Poirot smiled, remembering MacQueen’s strictures on “Britishers.”

“–but I liked this young fellow. He’d got hold of some tomfool idiotic ideas about the situation in India. That’s the worst of Americans – they’re so sentimental and idealistic. Well, he was interested in what I had to tell him. I’ve had nearly thirty years’ experience of the country. And I was interested in what he had to tell me about the working of Prohibition in America. Then we got down to world politics in general. I was quite surprised to look at my watch and find it was a quarter to two.”

“That is the time you broke up this conversation?”

“Yes.”

“What did you do then?”

“Walked along to my own compartment and turned in.”

“Your bed was made up ready?”

“Yes.”

“That is the compartment – let me see – No. 15 – the one next but one to the end away from the dining-car?”

“Yes.”

“Where was the conductor when you went to your compartment?”

“Sitting at the end at a little table. As a matter of fact MacQueen called him just as I went in to my own compartment.”

“Why did he call him?”

“To make up his bed, I suppose. The compartment hadn’t been made up for the night.”

“Now, Colonel Arbuthnot, I want you to think carefully. During the time you were talking to Mr. MacQueen, did anyone pass along the corridor outside the door?”

“A good many people, I should think. I wasn’t paying attention.”

“Ah! but I am referring to – let us say, the last hour and a half of your conversation. You got out at Vincovci, didn’t you?”

“Yes, but only for about a minute. There was a blizzard on. The cold was something frightful. Made one quite thankful to get back to the fug, though as a rule I think the way these trains are overheated is something scandalous.”

M. Bouc sighed. “It is very difficult to please everybody,” he said. “The English they open everything – then others they come along and shut everything. It is very difficult.”

Neither Poirot nor Colonel Arbuthnot paid any attention to him.

“Now, Monsieur, cast your mind back,” said Poirot encouragingly. “It was cold outside. You have returned to the train. You sit down again, you smoke – perhaps a cigarette – perhaps a pipe–”

He paused for the fraction of a second.

“A pipe for me. MacQueen smoked cigarettes.”

“The train starts again. You smoke your pipe. You discuss the state of Europe – of the world. It is late now. Most people have retired for the night. Does anyone pass the door? Think.”

Arbuthnot frowned in the effort of remembrance.

“Difficult to say,” he said. “You see I wasn’t paying any attention.”

“But you have the soldier’s observation for detail. You notice without noticing, so to speak.”

The Colonel thought again, but shook his head.

“I couldn’t say. I don’t remember anyone passing except the conductor. Wait a minute – and there was a woman, I think.”

“You saw her? Was she old – young?”

“Didn’t see her. Wasn’t looking that way, just a rustle and a sort of smell of scent.”

“Scent? A good scent?”

“Well, rather fruity, if you know what I mean. I mean you’d smell it a hundred yards away. But mind you,” the Colonel went on hastily, “this may have been earlier in the evening. You see, as you said just now, it was just one of those things you notice without noticing, so to speak. Some time that evening I said to myself – ‘Woman-scent-got it on pretty thick.’ But when it was I can’t be sure, except that – why, yes, it must have been after Vincovci.”

“Why?”

“Because I remember – sniffing, you know – just when I was talking about the utter washout Stalin’s Five Year Plan was turning out. I know the idea woman brought the idea of the position of women in Russia into my mind. And I know we hadn’t got on to Russia until pretty near the end of our talk.”

“You can’t pin it down more definitely than that?”

“N-no. It must have been roughly within the last half-hour.”

“It was after the train had stopped?”

The other nodded. “Yes, I’m almost sure it was.”

“Well, we will pass from that. Have you ever been in America, Colonel Arbuthnot?”

“Never. Don’t want to go.”

“Did you ever know a Colonel Armstrong?”

“Armstrong – Armstrong – I’ve known two or three Armstrongs. There was Tommy Armstrong in the 60th – you don’t mean him? And Selby Armstrong – he was killed on the Somme.”

“I mean the Colonel Armstrong who married an American wife and whose only child was kidnapped and killed.”

“Ah, yes, I remember reading about that – shocking affair. I don’t think I actually ever came across the fellow, though of course I knew of him. Toby Armstrong. Nice fellow. Everybody liked him. He had a very distinguished career. Got the V.C.”

“The man who was killed last night was the man responsible for the murder of Colonel Armstrong’s child.”

Arbuthnot’s face grew rather grim. “Then in my opinion the swine deserved what he got. Though I would have preferred to see him properly hanged – or electrocuted, I suppose, over there.”

“In fact, Colonel Arbuthnot, you prefer law and order to private vengeance?”

“Well, you can’t go about having blood feuds and stabbing each other like Corsicans or the Mafia,” said the Colonel. “Say what you like, trial by jury is a sound system.”

Poirot looked at him thoughtfully for a minute or two.

“Yes,” he said. I am sure that would be your view. Well, Colonel Arbuthnot, I do not think there is anything more I have to ask you. There is nothing you yourself can recall last night that in any way snuck you – or shall we say strikes you now, looking back – as suspicious?”