we were sitting in a state of tense attention to listen to poirot’s final explanation of the case.

‘all along,’ he said, ‘i have been worried over the whyof this case. hastings said to me the other day that the case was ended. i replied to him that the case was the man!the mystery was not the mystery of the murders, but the mystery of a b c. why did he find it necessary to commit these murders? why did he select meas his adversary?

‘it is no answer to say that the man was mentally unhinged. to say a man does mad things because he is mad is merely unintelligent and stupid. a madman is as logical and reasoned in his actions as a sane man—given his peculiar biased point of view. for example, if a man insists on going out and squatting about in nothing but a loin cloth his conduct seems eccentric in the extreme. but once you know that the man himself isfirmly convinced that he is mahatma gandhi, then his conduct becomes perfectly reasonable and logical.

‘what was necessary in this case was to imagine a mind so constituted that it was logical and reasonable to commit four or more murdersand 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 canguess, 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 itis 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 didtake place.

‘there was no means at that point, as i well realized, of knowing who the personwas 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 personalreason? there was, discernible in the letter, a slight anti-foreignbias—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 needto commit these murders?’

megan barnard stirred in her chair.

‘isn’t there such a thing as—as a blood lust?’ she said.

poirot turned to her.

‘you are quite right, mademoiselle. there issuch a thing. the lust to kill. but that did not quite fit the facts of the case. a homicidal maniac who desires to kill usually desires to kill as many victims as possible. it is a recurring craving. the great idea of such a killer is to hide his tracks—not to advertisethem. when we consider the four victims selected—or at any rate three of them (for i know very little of mr downes or mr earlsfield), we realize that if he had chosen, the murderer could have done away with them without incurring any suspicion. franz ascher, donald fraser or megan barnard, possibly mr clarke—those are the people the police would have suspected even if they had been unable to get direct proof. an unknownhomicidal murderer would not have been thought of! why, then, did the murderer feel it necessary to call attention to himself? was it the necessity of leaving on each body a copy of an a b c railway guide? was thatthe compulsion? was there some complex connected with the railway guide?

‘i found it quite inconceivable at this point to enter into the mind of the murderer. surely it could not be magnanimity? a horror of responsibility for the crime being fastened on an innocent person?

‘although i could not answer the main question, certain things i did feel i was learning about the murderer.’

‘such as?’ asked fraser.

‘to begin with—that he had a tabular mind. his crimes were listed by alphabetical progression—that was obviously important to him. on the other hand, he had no particular taste in victims—mrs ascher, betty barnard, sir carmichael clarke, they all differed widely from each other. there was no sex complex—no particular age complex, and that seemed to me to be a very curious fact. if a man kills indiscriminately it is usually because he removes anyone who stands in his way or annoys him. but the alphabetical progression showed that such was not the case here. the other type of killer usually selects a particular type of victim—nearly always of the opposite sex. there was somethinghaphazard about the procedure of a b c that seemed to me to be at war with the alphabetical selection.

‘one slight inference i permitted myself to make. the choice of the a b c suggested to me what i may call a railway-minded man. this is more common in men than women. small boys love trains better than small girls do. it might be the sign, too, of an in some ways undeveloped mind. the “boy” motif still predominated.

‘the death of betty barnard and the manner of it gave me certain other indications. the manner of her death was particularly suggestive. (forgive me, mr fraser.) to begin with, she was strangled with her own belt—therefore she must almost certainly have been killed by someone with whom she was on friendly or affectionate terms. when i learnt something of her character a picture grew up in my mind.

‘betty barnard was a flirt. she liked attention from a personable male. therefore a b c, to persuade her to come out with him, must have had a certain amount of attraction—of le sex appeal!he must be able, as you english say, to “get off”. he must be capable of the click! i visualize the scene on the beach thus: the man admires her belt. she takes it off, he passes it playfully round her neck—says, perhaps, “i shall strangle you.” it is all very playful. she giggles—and he pulls—’

donald fraser sprang up. he was livid.

‘m. poirot—for god’s sake.’

poirot made a gesture.

‘it is finished. i say no more. it is over. we pass to the next murder, that of sir carmichael clarke. here the murderer goes back to his first method—the blow on the head. the same alphabetical complex—but one fact worries me a little. to be consistent the murderer should have chosen his towns in some definite sequence.

‘if andover is the 155th name under a, then the b crime should be the 155th also—or it should be the 156th and the c the 157th. here again the towns seemed to be chosen in rather too haphazarda fashion.’

‘isn’t that because you’re rather biased on that subject, poirot?’ i suggested. ‘you yourself are normally methodical and orderly. it’s almost a disease with you.’

‘no, it is nota disease! quelle idée!but i admit that i may be over-stressing that point. passons!

‘the churston crime gave me very little extra help. we were unlucky over it, since the letter announcing it went astray, hence no preparations could be made.

‘but by the time the d crime was announced, a very formidable system of defence had been evolved. it must have been obvious that a b c could not much longer hope to get away with his crimes.

‘moreover, it was at this point that the clue of thestockings came into my hand. it was perfectly clear that the presence of an individual selling stockings on and near the scene of each crime could not be a coincidence. hence the stocking-seller must be the murderer. i may say that his description, as given me by miss grey, did not quite correspond with my own picture of the man who strangled betty barnard.

‘i will pass over the next stages quickly. a fourth murder was committed—the murder of a man named george earlsfield—it was supposed in mistake for a man named downes, who was something of the same build and who was sitting near him in the cinema.

‘and now at last comes the turn of the tide. events play against a b c instead of into his hands. he is marked down—hunted—and at last arrested.

‘the case, as hastings says, is ended!

‘true enough as far as the public is concerned. the man is in prison and will eventually, no doubt, go to broadmoor. there will be no more murders. exit! finis! r.i.p.

‘but not for me!i know nothing—nothing at all! neither the whynor the wherefore

‘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 airof being genuine. but it cannot be genuine unless—and now we come to two very interesting speculations.

‘supposing, my friends, that while cust committed threeof 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 25th—the day he had arrived for the crime. supposing someone had forestalled him? what in those circumstances would he do? commit a secondmurder, 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 musthave 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 havetaken advantage of the crimes committed by other people. not all the crimes of jackthe 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 notresponsible for the killing of betty barnard? supposing that someone elsekilled 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 si!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 vérité, 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 groupof 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. iwas 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 pin-cushion! 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. notmr 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-like 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 oneof the crimes!

‘consider when a man or woman is killed, what are the questions that the police ask? opportunity. where everybody was 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 timein some way? but that is always a hazardous proceeding. our murderer thought of a more fantastic defence. create a homicidalmurderer!

‘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 outsuch 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 holidays earlyin august, which rendered it unlikely 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 girl in a café. 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 tastein fiction—i have ascertained that there is a book in the library called the railway childrenby 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 brainsto 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 daring—and the pseudomurderer, stupid, vacillating and suggestible.

‘suggestible—it is in that word that the mystery of mr cust consists! it was not enough for you, mr clarke,to devise this plan of a seriesto distract attention from a singlecrime. you had also to have a stalking horse.

‘i think the idea first originated in your mind as the result of a chance encounter in a city coffee den with this odd personality with his bombastic christian names. you were at that time turning over in your mind various plans for the murder of your brother.’

‘really? and why?’

‘because you were seriously alarmed for the future. i do not know whether you realize it, mr clarke, but you played into my hands when you showed me a certain letter written to you by your brother. in it he displayed very clearly his affection and absorption in miss thora grey. his regard may have been a paternal one—or he may have preferred to think it so. nevertheless, there was a very real danger that on the death of your sister-in-law he might, in his loneliness, turn to this beautiful girl for sympathy and comfort and it might end—as so often happens with elderly men—in his marrying her. your fear was increased by your knowledge of miss grey. you are, i fancy, an excellent, if somewhat cynical judge of character. you judged, whether correctly or not, that miss grey was a type of young woman “on the make”. you had no doubt that she would jump at the chance of becoming lady clarke. your brother was an extremely healthy and vigorous man. there might be children andyour chance of inheriting your brother’s wealth would vanish.

‘you have been, i fancy, in essence a disappointed man all your life. you have been the rolling stone—and you have gathered very little moss. you were bitterly jealous of your brother’s wealth.

‘i repeat then that, turning over various schemes in your mind, your meeting with mr cust gave you an idea. his bombastic christian names, his account of his epileptic seizures and of his headaches, his whole shrinking and insignificant personality, struck you as fitting him for the tool you wanted. the whole alphabetical plan sprang into your mind—cust’s initials—the fact that your brother’s name began with a c and that he lived at churston were the nucleus of the scheme. you even went so far as to hint to cust at his possible end—though you could hardly hope that that suggestion would bear the rich fruit that it did!

‘your arrangements were excellent. in cust’s name you wrote for a large consignment of hosiery to be sent to him. you yourself sent a number of a b c’s looking like a similar parcel. you wrote to him—a typed letter purporting to be from the same firm offering him a good salary and commission. your plans were so well laid beforehand that you typed all the letters that were sent subsequently, and then presented him with the machine on which they had been typed

‘you had now to look about for two victims whose names began with a and b respectively and who lived at places also beginning with those same letters.

‘you hit on andover as quite a likely spot and your preliminary reconnaissance there led you to select mrs ascher’s shop as the scene of the first crime. her name was written clearly over the door, and you found by experiment that she was usually alone in the shop. her murder needed nerve, daring and reasonable luck.

‘for the letter b you had to vary your tactics. lonely women in shops might conceivably have been warned. i should imagine that you frequented a few cafés and tea-shops, laughing and joking with the girls there and finding out whose name began with the right letter and who would be suitable for your purpose.

‘in betty barnard you found just the type of girl you were looking for. you took her out once or twice, explaining to her that you were a married man, and that outings must therefore take place in a somewhat hole-and-corner manner.

‘then, your preliminary plans completed, you set to work! you sent the andover list to cust, directing him to go there on a certain date, and you sent off the first a b c letter to me.

‘on the appointed day you went to andover—and killed mrs ascher—without anything occurring to damage your plans.

‘murder no. 1 was successfully accomplished.

‘for the second murder, you took the precaution of committing it, in reality, the day before. i am fairly certain that betty barnard was killed well before midnight on the 24th july.

‘we now come to murder no. 3—the important—in fact, the realmurder from your point of view.

‘and here a full meed of praise is due to hastings, who made a simple and obvious remark to which no attention was paid.

‘he suggested that the third letter went astray intentionally!

‘and he was right!…

‘in that one simple fact lies the answer to the question that has puzzled me so all along. why were the letters addressed in the first place to hercule poirot, a private detective, and not to the police?

‘erroneously i imagined some personal reason.

‘not at all! the letters were sent to me because the essence of your plan was that one of them should be wrongly addressed and go astray—but you cannot arrange for a letter addressed to the criminal investigation department of scotland yard to go astray! it is necessary to have a privateaddress. you chose me as a fairly well-known person, and a person who was sure to take the letters to the police—and also, in your rather insular mind, you enjoyed scoring off a foreigner.

‘you addressed your envelope very cleverly—whitehaven—whitehorse—quite a natural slip. only hastings was sufficiently perspicacious to disregard subtleties and go straight for the obvious!

‘of course the letter was meantto go astray! the police were to be set on the trail only when the murder was safely over. your brother’s nightly walk provided you with the opportunity. and so successfully had the a b c terror taken hold on the public mind that the possibility of your guilt never occurred to anyone.

‘after the death of your brother, of course, your object was accomplished. you had no wish to commit any more murders. on the other hand, if the murders stopped without reason, a suspicion of the truth might come to someone.

‘your stalking horse, mr cust, had so successfully lived up to his role of the invisible—because insignificant—man, that so far no one had noticed that the same person had been seen in the vicinity of the three murders! to your annoyance, even his visit to combeside had not been mentioned. the matter had passed completely out of miss grey’s head.

‘always daring, you decided that one more murder must take place but this time the trail must be well blazed.

‘you selected doncaster for the scene of operations.

‘your plan was very simple. you yourself wouldbe on the scene in the nature of things. mr cust would be ordered to doncaster by his firm. your plan was to follow him round and trust to opportunity. everything fell out well. mr cust went to a cinema. that was simplicity itself. you sat a few seats away from him. when he got up to go, you did the same. you pretended to stumble, leaned over and stabbed a dozing man in the row in front, slid the a b c on to his knees and managed to collide heavily with mr cust in the darkened doorway, wiping the knife on his sleeve and slipping it into his pocket.

‘you were not in the least at pains to choose a victim whose name began with d. anyone would do! you assumed—and quite rightly—that it would be considered to be a mistake. there was sure to be someone whose name began with d not far off in the audience. it would be assumed that he had been intended to be the victim.

‘and now, my friends, let us consider the matter from the point of view of the false a b c—from the point of view of mr cust.

‘the andover crime means nothing to him. he is shocked and surprised by the bexhill crime—why, he himself was there about the time! then comes the churston crime and the headlines in the newspapers. an a b c crime at andover when he was there, an a b c crime at bexhill, and now another close by…threecrimes and he has been at the scene of each of them.persons suffering from epilepsy often have blanks when they cannot remember what they have done…remember that cust was a nervous, highly neurotic subject and extremely suggestible.

‘then he receives the order to go to doncaster.

‘doncaster! and the next a b c crime is to be in doncaster. he must have felt as though it was fate. he loses his nerve, fancies his landlady is looking at him suspiciously, and tells her he is going to cheltenham.

‘he goes to doncaster because it is his duty. in the afternoon he goes to a cinema. possibly he dozes off for a minute or two.

‘imagine his feelings when on his return to his inn he discovers that there is blood on his coat sleeve and a blood-stained knife in his pocket. all his vague forebodings leap into certainty.

‘he—he himself—is the killer!he remembers his headaches—his lapses of memory. he is quite sure of the truth—he, alexander bonaparte cust, is a homicidal lunatic

‘his conduct after that is the conduct of a hunted animal. he gets back to his lodgings in london. he is safe there—known. they think he has been in cheltenham. he has the knife with him still—a thoroughly stupid thing to do, of course. he hides it behind the hall stand.

‘then, one day, he is warned that the police are coming. it is the end! they know!

‘the hunted animal does his last run…

‘i don’t know why he went to andover—a morbid desire, i think, to go and look at the place where the crime was committed—the crime hecommitted though he can remember nothing about it…

‘he has no money left—he is worn out…his feet lead him of his own accord to the police station.

‘but even a cornered beast will fight. mr cust fully believes that he did the murders but he sticks strongly to his plea of innocence. and he holds with desperation to that alibi for the second murder. at least that cannot be laid to his door.

‘as i say, when i saw him, i knew at once that he was notthe murderer and that my name meantnothing to him. i knew, too, that he thoughthimself the murderer!

‘after he had confessed his guilt to me, i knew more strongly than ever that my own theory was right.’

‘your theory,’ said franklin clarke, ‘is absurd!’

poirot shook his head.

‘no, mr clarke. you were safe enough so long as no one suspected you. once you weresuspected proofs were easy to obtain.’

‘proofs?’

‘yes. i found the stick that you used in the andoverand churston murders in a cupboard at combeside. an ordinary stick with a thick knob handle. a section of wood had been removed and melted lead poured in. your photograph was picked out from half a dozen others by two people who saw you leaving the cinema when you were supposed to be on the race-course at doncaster. you were identified at bexhill the other day by milly higley and a girl from the scarlet runner roadhouse, where you took betty barnard to dine on the fatal evening. and finally—most damning of all—you overlooked a most elementary precaution. you left a fingerprint on cust’s typewriter—the typewriter that, if you are innocent, you could never have handled.’

clarke sat quite still for a minute, then he said:

‘rouge, impair, manque!—you win, m. poirot! but it was worth trying!’

with an incredibly rapid motion he whipped out a small automatic from his pocket and held it to his head.

i gave a cry and involuntarily flinched as i waited for the report.

but no report came—the hammer clicked harmlessly.

clarke stared at it in astonishment and uttered an oath.

‘no, mr clarke,’ said poirot. ‘you may have noticed i had a new manservant today—a friend of mine—anexpert sneak thief. he removed your pistol from your pocket, unloaded it, and returned it, all without you being aware of the fact.’

‘you unutterable little jackanapes of a foreigner!’ cried clarke, purple with rage.

‘yes, yes, that is how you feel. no, mr clarke, no easy death for you. you told mr cust that you had had near escapes from drowning. you know what that means—that you were born for another fate.’

‘you—’

words failed him. his face was livid. his fists clenched menacingly.

two detectives from scotland yard emerged from the next room. one of them was crome. he advanced and uttered his time-honoured formula: ‘i warn you that anything you say may be used as evidence.’

‘he has said quite enough,’ said poirot, and he added to clarke: ‘you are very full of an insular superiority, but for myself i consider your crime not an english crime at all—not above-board—not sporting—’