‘What was necessary in this case was to imagine a mind so constituted that it was logical and reasonable to commit four or more murders and to announce them beforehand by letters written to Hercule Poirot.

‘My friend Hastings will tell you that from the moment I received the first letter I was upset and disturbed. It seemed to me at once that there was something very wrong about the letter.’

‘You were quite right,’ said Franklin Clarke dryly.

‘Yes. But there, at the very start, I made a grave error. I permitted my feeling—my very strong feeling about the letter—to remain a mere impression. I treated it as though it had been an intuition. In a well-balanced, reasoning mind there is no such thing as an intuition—an inspired guess! You can guess, of course—and a guess is either right or wrong. If it is right you call it an intuition. If it is wrong you usually do not speak of it again. But what is often called an intuition is really an impression based on logical deduction or experience. When an expert feels that there is something wrong about a picture or a piece of furniture or the signature on a cheque he is really basing that feeling on a host of small signs and details. He has no need to go into them minutely—his experience obviates that—the net result is the definite impression that something is wrong. But it is not a guess, it is an impression based on experience.

‘Eh bien, I admit that I did not regard that first letter in the way I should. It just made me extremely uneasy. The police regarded it as a hoax. I myself took it seriously. I was convinced that a murder would take place in Andover as stated. As you know, a murder did take place.

‘There was no means at that point, as I well realized, of knowing who the person was who had done the deed. The only course open to me was to try and understand just what kind of a person had done it.

‘I had certain indications. The letter—the manner of the crime—the person murdered. What I had to discover was: the motive of the crime, the motive of the letter.’

‘Publicity,’ suggested Clarke.

‘Surely an inferiority complex covers that,’ added Thora Grey.

‘That was, of course, the obvious line to take. But why me? Why Hercule Poirot? Greater publicity could be ensured by sending the letters to Scotland Yard. More again by sending them to a newspaper. A newspaper might not print the first letter, but by the time the second crime took place, A B C could have been assured of all the publicity the press could give. Why, then, Hercule Poirot? Was it for some personal reason? There was, discernible in the letter, a slight anti-foreign bias—but not enough to explain the matter to my satisfaction.

‘Then the second letter arrived—and was followed by the murder of Betty Barnard at Bexhill. It became clear now (what I had already suspected) that the murders were to proceed on an alphabetical plan, but the fact, which seemed final to most people, left the main question unaltered to my mind. Why did A B C need to commit these murders?’