“George and Harriet Sippel,” I read aloud. “Patrick and Frances Ive. Patrick Ive and Nancy Ducane. William Ducane and Nancy Ducane. Charles and Margaret Ernst. Richard Negus and Ida Gransbury. In none of these pairings is the woman older than the man, certainly not by enough to be described as ‘old enough to be his mother.’ ”

“Tsk,” said Poirot impatiently. “You do not think, my friend. How do you know that this couple exists, with the older woman and the younger man?”

I stared at him, wondering if he had lost his reason. “Well, Walter Stoakley talked about them at the King’s Head, and Rafal Bobak overheard—”

“Non, non,” Poirot interrupted gracelessly. “You do not pay attention to the details: in the King’s Head Inn, Walter Stoakley spoke of the woman putting an end to her romantic involvement with the man, did he not? Whereas the conversation that Rafal Bobak overheard between the three murder victims was about a man no longer romantically interested in a woman who still craved his love. How can these be the same people, the same couple? The very opposite must be true: they cannot possibly be the same people!”

“You’re right,” I said, dejected. “I didn’t think of that.”

“You were too delighted with your pattern—that is why. A much older woman and much younger man over here, and a much older woman and much younger man over there. Voilà, you assume they must be the same!”

“Yes, I did. Perhaps I’m in the wrong job.”

“Non. You are perceptive, Catchpool. Not always, but sometimes. You have helped to steer me through the tunnel of confusion. Do you remember when you said that whatever Thomas Brignell was withholding, he was doing so for reasons of personal embarrassment? That was a remark that proved very helpful to me—very helpful indeed!”

“Well, I’m afraid I’m still in the tunnel and can’t see a flicker of light at either end.”

“I will make you a promise,” said Poirot. “Tomorrow, immediately after breakfast, we will pay a little visit, you and I. After that, you will comprehend more than you do now. I hope that I will also.”

“I don’t suppose I am permitted to ask whom we will be visiting?”

“You may ask, mon ami.” Poirot smiled. “I telephoned to Scotland Yard for the address. It is one you would recognize, I think, if I told it to you.”

Which, needless to say, he had no intention of doing.

18. Knock and See Who Comes to the Door

Knock and See Who Comes to the Door