"And there is one small vexing fact. The man Cust has an alibi for the night of the Bexhill crime."

"That's been worrying me all along," said Franklin Clarke.

"Yes. It worried me. For the alibi, it has the air of being genuine. But it cannot be genuine unless—and now we come to two very interesting speculations."

"Supposing, my friends, that while Cust committed three of the crimes—the A, C and D crimes—he did not commit the B crime."

"M. Poirot. It isn't—"

Poirot silenced Megan Barnard with a look. "Be quiet, mademoiselle. I am for the truth, I am! I have done with lies. Supposing, I say, that A.B.C. did not commit the second crime. It took place, remember, in the early hours of the 25^th—the day he had arrived for the crime. Supposing someone had forestalled him? What in those circumstances would he do? Commit a second murder, or lie low and accept the first as a kind of macabre present?"

"M. Poirot!" said Megan. "That's a fantastic thought! All the crimes must have been committed by the same person!"

He took no notice of her and went steadily on: "Such a hypothesis had the merit of explaining one fact—the discrepancy between the personality of Alexander Bonaparte Cust (who could never have made the click with any girl) and the personality of Betty Barnard's murderer. And it has been known, before now, that would-be murderers have taken advantage of the crimes committed by other people. Not all the crimes of Jack the Ripper were committed by Jack the Ripper, for instance. So far, so good."

"But then I came up against a definite difficulty."

"Up to the time of the Barnard murder, no facts about the A.B.C. murders had been made public. The Andover murder had created little interest. The incident of the open railway guide had not even been mentioned in the press. It therefore followed that whoever killed Betty Barnard must have had access to facts known only to certain persons—myself, the police, and certain relations and neighbours of Mrs. Ascher."

"That line of research seemed to lead me up against a blank wall."

The faces that looked at him were blank too. Blank and puzzled.

Donald Fraser said thoughtfully: "The police, after all, are human beings. And they're good-looking men—"

He stopped, looking at Poirot inquiringly.

Poirot shook his head gently. "No—it is simpler than that. I told you that there was a second speculation."

"Supposing that Cust was not responsible for the killing of Betty Barnard? Supposing that someone else killed her. Could that someone else have been responsible for the other murders too?"

"But that doesn't make sense!" cried Clarke.

"Doesn't it? I did then what I ought to have done at first. I examined the letters I had received from a totally different point of view. I had felt from the beginning that there was something wrong with them—just as a picture expert knows a picture is wrong . . . ."

"I had assumed, without pausing to consider, that what was wrong with them was the fact that they were written by a madman."

"Now I examined them again—and this time I came to a totally different conclusion. What was wrong with them was the fact that they were written by a sane man!"

"What?" I cried.

"But yes—just that precisely! They were wrong as a picture is wrong—because they were a fake. They pretended to be the letters of a madman—of a homicidal lunatic, but in reality they were nothing of the kind."

"It doesn't make sense," Franklin Clarke repeated.

"Mais oui. One must reason—reflect. What would be the object of writing such letters? To focus attention on the writer, to call attention to the murders! En veritй, it did not seem to make sense at first sight. And then I saw light. It was to focus attention on several murders—on a group of murders . . . . Is it not your great Shakespeare who has said, 'You cannot see the trees for the wood'?"

I did not correct Poirot's literary reminiscences. I was trying to see his point. A glimmer came to me. He went on: "When do you notice a pin least? When it is in a pincushion! When do you notice an individual murder least? When it is one of a series of related murders."

"I had to deal with an intensely clever, resourceful murderer—reckless, daring and a thorough gambler. Not Mr. Cust! He could never have committed these murders! No, I had to deal with a very different stamp of man—a man with a boyish temperament (witness the schoolboy-type letters and the railway guide), an attractive man to women, and a man with a ruthless disregard for human life, a man who was necessarily a prominent person in one of the crimes! Consider when a man or woman is killed, what are the questions that the police ask? Opportunity. Where was everybody at the time of the crime? Motive. Who benefited by the deceased's death? If the motive and the opportunity are fairly obvious, what is a would-be murderer to do? Fake an alibi—that is, manipulate time in some way? But that is always a hazardous proceeding. Our murderer thought of a more fantastic defence."

"Create a homicidal murderer!"

"I had now only to review the various crimes and find the possible guilty person. The Andover crime? The most likely suspect for that was Franz Ascher, but I could not imagine Ascher inventing and carrying out such an elaborate scheme, nor could I see him planning a premeditated murder. The Bexhill crime? Donald Fraser was a possibility."

"He had brains and ability, and a methodical turn of mind. But his motive for killing his sweetheart could only be jealousy—and jealousy does not tend to premeditation. Also I learned that he had his holiday early in August, which rendered it unlikely that he had anything to do with the Churston crime. We come to the Churston crime next—and at once we are on infinitely more promising ground."

"Sir Carmichael Clarke was an immensely wealthy man. Who inherits his money? His wife, who is dying, has a life interest in it, and it then goes to his brother Franklin."

Poirot turned slowly round till his eyes met those of Franklin Clarke.

"I was quite sure then. The man I had known a long time in my secret mind was the same as the man whom I had known as a person."

"A.B.C. and Franklin Clarke were one and the same. The daring adventurous character, the roving life, the partiality for England that had showed itself, very faintly, in the jeer at foreigners. The attractive free and easy manner—nothing easier for him than to pick up a gift in a cafй. The methodical tabular mind—he made a list here one day, ticked off over the headings A.B.C.—and finally, the boyish mind—mentioned by Lady Clarke and even shown by his taste in fiction—I have ascertained that there is a book in the library called The Railway Children by E. Nesbit. I had no further doubt in my own mind—A.B.C., the man who wrote the letters and committed the crimes, was Franklin Clarke."

Clarke suddenly burst out laughing. "Very ingenious! And what about our friend Cust, caught red-handed?"

"What about the blood on his coat? And the knife he hid in his lodgings? He may deny he committed the crimes—"

Poirot interrupted. "You are quite wrong. He admits the fact."

"What?" Clarke looked really startled.

"Oh, yes," said Poirot gently. "I had no sooner spoken to him than I was aware that Cust believed himself to be guilty."

"And even that didn't satisfy M. Poirot?" said Clarke.

"No. Because as soon as I saw him I also knew that he could not be guilty! He has neither the nerve nor the daring—nor, I may add, the brains to plan! All along I have been aware of the dual personality of the murderer. Now I see wherein it consisted. Two people were involved—the real murderer, cunning, resourceful and calculating—and the pseudo murderer, stupid, vacillating and suggestible."