There is somewhere in Brompton or Kensington an interminable avenue of tall houses, rich but largely empty, that looks like a terrace of tombs.  The very steps up to the dark front doors seem as steep as the side of pyramids; one would hesitate to knock at the door, lest it should be opened by a mummy.  But a yet more depressing feature in the grey façade is its telescopic length and changeless continuity.  The pilgrim walking down it begins to think he will never come to a break or a corner; but there is one exception -a very small one, but hailed by the pilgrim almost with a shout.  There is a sort of mews between two of the tall mansions, a mere slit like the crack of a door by comparison with the street, but just large enough to permit a pigmy ale-house or eating-house, still allowed by the rich to their stable-servants, to stand in the angle.  There is something cheery in its very dinginess, and something free and elfin in its very insignificance.  At the feet of those grey stone giants it looks like a lighted house of dwarfs.

Anyone passing the place during a certain autumn evening, itself almost fairylike, might have seen a hand pull aside the red half-blind which (along with some large white lettering) half hid the interior from the street, and a face peer out not unlike a rather innocent goblin’s.  It was, in fact, the face of one with the harmless human name of Brown, formerly priest of Cobhole in Essex, and now working in London.  His friend, Flambeau, a semi-official investigator, was sitting opposite him, making his last notes of a case he had cleared up in the neighbourhood.  They were sitting at a small table, close up to the window, when the priest pulled the curtain back and looked out.  He waited till a stranger in the street had passed the window, to let the curtain fall into its place again.  Then his round eyes rolled to the large white lettering on the window above his head, and then strayed to the next table, at which sat only a navvy with beer and cheese, and a young girl with red hair and a glass of milk.  Then (seeing his friend put away the pocket-book), he said softly: 

“If you’ve got ten minutes, I wish you’d follow that man with the false nose.”

Flambeau looked up in surprise; but the girl with the red hair also looked up, and with something that was stronger than astonishment.  She was simply and even loosely dressed in light brown sacking stuff; but she was a lady, and even, on a second glance, a rather needlessly haughty one.  “The man with the false nose!” repeated Flambeau.  “Who’s he?”

“I haven’t a notion,” answered Father Brown.  “I want you to find out; I ask it as a favour.  He went down there” -and he jerked his thumb over his shoulder in one of his undistinguished gestures -“and can’t have passed three lamp-posts yet.  I only want to know the direction.”

Flambeau gazed at his friend for some time, with an expression between perplexity and amusement; and then, rising from the table; squeezed his huge form out of the little door of the dwarf tavern, and melted into the twilight.

Father Brown took a small book out of his pocket and began to read steadily; he betrayed no consciousness of the fact that the red-haired lady had left her own table and sat down opposite him.  At last she leaned over and said in a low, strong voice:  “Why do you say that?  How do you know it’s false?”

He lifted his rather heavy eyelids, which fluttered in considerable embarrassment.  Then his dubious eye roamed again to the white lettering on the glass front of the public-house.  The young woman’s eyes followed his, and rested there also, but in pure puzzledom.

“No,” said Father Brown, answering her thoughts.  “It doesn’t say ‘Sela’, like the thing in the Psalms; I read it like that myself when I was wool-gathering just now; it says ‘Ales.’”

“Well?” inquired the staring young lady.  “What does it matter what it says?”

His ruminating eye roved to the girl’s light canvas sleeve, round the wrist of which ran a very slight thread of artistic pattern, just enough to distinguish it from a working-dress of a common woman and make it more like the working-dress of a lady art-student.  He seemed to find much food for thought in this; but his reply was very slow and hesitant.  “You see, madam,” he said, “from outside the place looks -well, it is a perfectly decent place -but ladies like you don’t -don’t generally think so.  They never go into such places from choice, except -”

“Well?” she repeated.

“Except an unfortunate few who don’t go in to drink milk.”

“You are a most singular person,” said the young lady.  “What is your object in all this?”

“Not to trouble you about it,” he replied, very gently.  “Only to arm myself with knowledge enough to help you, if ever you freely ask my help.”

“But why should I need help?”

He continued his dreamy monologue.  “You couldn’t have come in to see protegees, humble friends, that sort of thing, or you’d have gone through into the parlour...and you couldn’t have come in because you were ill, or you’d have spoken to the woman of the place, who’s obviously respectable...besides, you don’t look ill in that way, but only unhappy....  This street is the only original long lane that has no turning; and the houses on both sides are shut up....  I could only suppose that you’d seen somebody coming whom you didn’t want to meet; and found the public-house was the only shelter in this wilderness of stone....  I don’t think I went beyond the licence of a stranger in glancing at the only man who passed immediately after....  And as I thought he looked like the wrong sort...and you looked like the right sort....  I held myself ready to help if he annoyed you; that is all.  As for my friend, he’ll be back soon; and he certainly can’t find out anything by stumping down a road like this....  I didn’t think he could.”

“Then why did you send him out?” she cried, leaning forward with yet warmer curiosity.  She had the proud, impetuous face that goes with reddish colouring, and a Roman nose, as it did in Marie Antoinette.

He looked at her steadily for the first time, and said:  “Because I hoped you would speak to me.”

She looked back at him for some time with a heated face, in which there hung a red shadow of anger; then, despite her anxieties, humour broke out of her eyes and the corners of her mouth, and she answered almost grimly:  “Well, if you’re so keen on my conversation, perhaps you’ll answer my question.”  After a pause she added:  “I had the honour to ask you why you thought the man’s nose was false.”

“The wax always spots like that just a little in this weather,” answered Father Brown with entire simplicity.

“But it’s such a crooked nose,” remonstrated the red-haired girl.

The priest smiled in his turn.  “I don’t say it’s the sort of nose one would wear out of mere foppery,” he admitted.  “This man, I think, wears it because his real nose is so much nicer.”

“But why?” she insisted.

“What is the nursery-rhyme?” observed Brown absent-mindedly.  “There was a crooked man and he went a crooked mile....  That man, I fancy, has gone a very crooked road -by following his nose.”

“Why, what’s he done?” she demanded, rather shakily.

“I don’t want to force your confidence by a hair,” said Father Brown, very quietly.  “But I think you could tell me more about that than I can tell you.”

The girl sprang to her feet and stood quite quietly, but with clenched hands, like one about to stride away; then her hands loosened slowly, and she sat down again.  “You are more of a mystery than all the others,” she said desperately, “but I feel there might be a heart in your mystery.”

“What we all dread most,” said the priest in a low voice, “is a maze with no centre.  That is why atheism is only a nightmare.”  “I will tell you everything,” said the red-haired girl doggedly, “except why I am telling you; and that I don’t know.”

She picked at the darned table-cloth and went on:  “You look as if you knew what isn’t snobbery as well as what is; and when I say that ours is a good old family, you’ll understand it is a necessary part of the story; indeed, my chief danger is in my brother’s high-and-dry notions, noblesse oblige and all that.  Well, my name is Christabel Carstairs; and my father was that Colonel Carstairs you’ve probably heard of, who made the famous Carstairs Collection of Roman coins.  I could never describe my father to you; the nearest I can say is that he was very like a Roman coin himself.  He was as handsome and as genuine and as valuable and as metallic and as out-of-date.  He was prouder of his Collection than of his coat-of-arms -nobody could say more than that.  His extraordinary character came out most in his will.  He had two sons and one daughter.  He quarrelled with one son, my brother Giles, and sent him to Australia on a small allowance.  He then made a will leaving the Carstairs Collection, actually with a yet smaller allowance, to my brother Arthur.  He meant it as a reward, as the highest honour he could offer, in acknowledgement of Arthur’s loyalty and rectitude and the distinctions he had already gained in mathematics and economics at Cambridge.  He left me practically all his pretty large fortune; and I am sure he meant it in contempt.

“Arthur, you may say, might well complain of this; but Arthur is my father over again.  Though he had some differences with my father in early youth, no sooner had he taken over the Collection than he became like a pagan priest dedicated to a temple.  He mixed up these Roman halfpence with the honour of the Carstairs family in the same stiff, idolatrous way as his father before him.  He acted as if Roman money must be guarded by all the Roman virtues.  He took no pleasures; he spent nothing on himself; he lived for the Collection.  Often he would not trouble to dress for his simple meals; but pattered about among the corded brown-paper parcels (which no one else was allowed to touch) in an old brown dressing-gown.  With its rope and tassel and his pale, thin, refined face, it made him look like an old ascetic monk.  Every now and then, though, he would appear dressed like a decidedly fashionable gentleman; but that was only when he went up to the London sales or shops to make an addition to the Carstairs Collection.

“Now, if you’ve known any young people, you won’t be shocked if I say that I got into rather a low frame of mind with all this; the frame of mind in which one begins to say that the Ancient Romans were all very well in their way.  I’m not like my brother Arthur; I can’t help enjoying enjoyment.  I got a lot of romance and rubbish where I got my red hair, from the other side of the family.  Poor Giles was the same; and I think the atmosphere of coins might count in excuse for him; though he really did wrong and nearly went to prison.  But he didn’t behave any worse than I did; as you shall hear.

“I come now to the silly part of the story.  I think a man as clever as you can guess the sort of thing that would begin to relieve the monotony for an unruly girl of seventeen placed in such a position.  But I am so rattled with more dreadful things that I can hardly read my own feeling; and don’t know whether I despise it now as a flirtation or bear it as a broken heart.  We lived then at a little seaside watering-place in South Wales, and a retired sea-captain living a few doors off had a son about five years older than myself, who had been a friend of Giles before he went to the Colonies.  His name does not affect my tale; but I tell you it was Philip Hawker, because I am telling you everything.  We used to go shrimping together, and said and thought we were in love with each other; at least he certainly said he was, and I certainly thought I was.  If I tell you he had bronzed curly hair and a falconish sort of face, bronzed by the sea also, it’s not for his sake, I assure you, but for the story; for it was the cause of a very curious coincidence.

“One summer afternoon, when I had promised to go shrimping along the sands with Philip, I was waiting rather impatiently in the front drawing-room, watching Arthur handle some packets of coins he had just purchased and slowly shunt them, one or two at a time, into his own dark study and museum which was at the back of the house.  As soon as I heard the heavy door close on him finally, I made a bolt for my shrimping-net and tam-o’-shanter and was just going to slip out, when I saw that my brother had left behind him one coin that lay gleaming on the long bench by the window.  It was a bronze coin, and the colour, combined with the exact curve of the Roman nose and something in the very lift of the long, wiry neck, made the head of Cæsar on it the almost precise portrait of Philip Hawker.  Then I suddenly remembered Giles telling Philip of a coin that was like him, and Philip wishing he had it.  Perhaps you can fancy the wild, foolish thoughts with which my head went round; I felt as if I had had a gift from the fairies.  It seemed to me that if I could only run away with this, and give it to Philip like a wild sort of wedding-ring, it would be a bond between us for ever; I felt a thousand such things at once.  Then there yawned under me, like the pit, the enormous, awful notion of what I was doing; above all, the unbearable thought, which was like touching hot iron, of what Arthur would think of it.  A Carstairs a thief; and a thief of the Carstairs treasure!  I believe my brother could see me burned like a witch for such a thing, But then, the very thought of such fanatical cruelty heightened my old hatred of his dingy old antiquarian fussiness and my longing for the youth and liberty that called to me from the sea.  Outside was strong sunlight with a wind; and a yellow head of some broom or gorse in the garden rapped against the glass of the window.  I thought of that living and growing gold calling to me from all the heaths of the world -and then of that dead, dull gold and bronze and brass of my brother’s growing dustier and dustier as life went by.  Nature and the Carstairs Collection had come to grips at last.

“Nature is older than the Carstairs Collection.  As I ran down the streets to the sea, the coin clenched tight in my fist, I felt all the Roman Empire on my back as well as the Carstairs pedigree.  It was not only the old lion argent that was roaring in my ear, but all the eagles of the Caesars seemed flapping and screaming in pursuit of me.  And yet my heart rose higher and higher like a child’s kite, until I came over the loose, dry sand-hills and to the flat, wet sands, where Philip stood already up to his ankles in the shallow shining water, some hundred yards out to sea.  There was a great red sunset; and the long stretch of low water, hardly rising over the ankle for half a mile, was like a lake of ruby flame.  It was not till I had torn off my shoes and stockings and waded to where he stood, which was well away from the dry land, that I turned and looked round.  We were quite alone in a circle of sea-water and wet sand, and I gave him the head of Cæsar.

“At the very instant I had a shock of fancy:  that a man far away on the sand-hills was looking at me intently.  I must have felt immediately after that it was a mere leap of unreasonable nerves; for the man was only a dark dot in the distance, and I could only just see that he was standing quite still and gazing, with his head a little on one side.  There was no earthly logical evidence that he was looking at me; he might have been looking at a ship, or the sunset, or the sea-gulls, or at any of the people who still strayed here and there on the shore between us.  Nevertheless, whatever my start sprang from was prophetic; for, as I gazed, he started walking briskly in a bee-line towards us across the wide wet sands.  As he drew nearer and nearer I saw that he was dark and bearded, and that his eyes were marked with dark spectacles.  He was dressed poorly but respectably in black, from the old black top hat on his head to the solid black boots on his feet.  In spite of these he walked straight into the sea without a flash of hesitation, and came on at me with the steadiness of a travelling bullet.

“I can’t tell you the sense of monstrosity and miracle I had when he thus silently burst the barrier between land and water.  It was as if he had walked straight off a cliff and still marched steadily in mid-air.  It was as if a house had flown up into the sky or a man’s head had fallen off.  He was only wetting his boots; but he seemed to be a demon disregarding a law of Nature.  If he had hesitated an instant at the water’s edge it would have been nothing.  As it was, he seemed to look so much at me alone as not to notice the ocean.  Philip was some yards away with his back to me, bending over his net.  The stranger came on till he stood within two yards of me, the water washing half-way up to his knees.  Then he said, with a clearly modulated and rather mincing articulation:  ’Would it discommode you to contribute elsewhere a coin with a somewhat different superscription?’

“With one exception there was nothing definably abnormal about him.  His tinted glasses were not really opaque, but of a blue kind common enough, nor were the eyes behind them shifty, but regarded me steadily.  His dark beard was not really long or wild -, but he looked rather hairy, because the beard began very high up in his face, just under the cheek-bones.  His complexion was neither sallow nor livid, but on the contrary rather clear and youthful; yet this gave a pink-and-white wax look which somehow (I don’t know why) rather increased the horror.  The only oddity one could fix was that his nose, which was otherwise of a good shape, was just slightly turned sideways at the tip; as if, when it was soft, it had been tapped on one side with a toy hammer.  The thing was hardly a deformity; yet I cannot tell you what a living nightmare it was to me.  As he stood there in the sunset-stained water he affected me as some hellish sea-monster just risen roaring out of a sea like blood.  I don’t know why a touch on the nose should affect my imagination so much.  I think it seemed as if he could move his nose like a finger.  And as if he had just that moment moved it.

“‘Any little assistance,’ he continued with the same queer, priggish accent, ’that may obviate the necessity of my communicating with the family.’

“Then it rushed over me that I was being blackmailed for the theft of the bronze piece; and all my merely superstitious fears and doubts were swallowed up in one overpowering, practical question.  How could he have found out?  I had stolen the thing suddenly and on impulse; I was certainly alone; for I always made sure of being unobserved when I slipped out to see Philip in this way.  I had not, to all appearance, been followed in the street; and if I had, they could not ‘X-ray’ the coin in my closed hand.  The man standing on the sand-hills could no more have seen what I gave Philip than shoot a fly in one eye, like the man in the fairy-tale.

“‘Philip,’ I cried helplessly, ‘ask this man what he wants.’

“When Philip lifted his head at last from mending his net he looked rather red, as if sulky or ashamed; but it may have been only the exertion of stooping and the red evening light; I may have only had another of the morbid fancies that seemed to be dancing about me.  He merely said gruffly to the man:  ‘You clear out of this.’  And, motioning me to follow, set off wading shoreward without paying further attention to him.  He stepped on to a stone breakwater that ran out from among the roots of the sand-hills, and so struck homeward, perhaps thinking our incubus would find it less easy to walk on such rough stones, green and slippery with seaweed, than we, who were young and used to it.  But my persecutor walked as daintily as he talked; and he still followed me, picking his way and picking his phrases.  I heard his delicate, detestable voice appealing to me over my shoulder, until at last, when we had crested the sand-hills, Philip’s patience (which was by no means so conspicuous on most occasions) seemed to snap.  He turned suddenly, saying, ‘Go back.  I can’t talk to you now.’  And as the man hovered and opened his mouth, Philip struck him a buffet on it that sent him flying from the top of the tallest sand-hill to the bottom.  I saw him crawling out below, covered with sand.

“This stroke comforted me somehow, though it might well increase my peril; but Philip showed none of his usual elation at his own prowess.  Though as affectionate as ever, he still seemed cast down; and before I could ask him anything fully, he parted with me at his own gate, with two remarks that struck me as strange.  He said that, all things considered, I ought to put the coin back in the Collection; but that he himself would keep it ‘for the present’.  And then he added quite suddenly and irrelevantly:  ‘You know Giles is back from Australia?’”

The door of the tavern opened and the gigantic shadow of the investigator Flambeau fell across the table.  Father Brown presented him to the lady in his own slight, persuasive style of speech, mentioning his knowledge and sympathy in such cases; and almost without knowing, the girl was soon reiterating her story to two listeners.  But Flambeau, as he bowed and sat down, handed the priest a small slip of paper.  Brown accepted it with some surprise and read on it:  “Cab to Wagga Wagga, 379, Mafeking Avenue, Putney.”  The girl was going on with her story.

“I went up the steep street to my own house with my head in a whirl; it had not begun to clear when I came to the doorstep, on which I found a milk-can -and the man with the twisted nose.  The milk-can told me the servants were all out; for, of course, Arthur, browsing about in his brown dressing-gown in a brown study, would not hear or answer a bell.  Thus there was no one to help me in the house, except my brother, whose help must be my ruin.  In desperation I thrust two shillings into the horrid thing’s hand, and told him to call again in a few days, when I had thought it out.  He went off sulking, but more sheepishly than I had expected -perhaps he had been shaken by his fall -and I watched the star of sand splashed on his back receding down the road with a horrid vindictive pleasure.  He turned a corner some six houses down.

“Then I let myself in, made myself some tea, and tried to think it out.  I sat at the drawing-room window looking on to the garden, which still glowed with the last full evening light.  But I was too distracted and dreamy to look at the lawns and flower-pots and flower-beds with any concentration.  So I took the shock the more sharply because I’d seen it so slowly.

“The man or monster I’d sent away was standing quite still in the middle of the garden.  Oh, we’ve all read a lot about pale-faced phantoms in the dark; but this was more dreadful than anything of that kind could ever be.  Because, though he cast a long evening shadow, he still stood in warm sunlight.  And because his face was not pale, but had that waxen bloom still upon it that belongs to a barber’s dummy.  He stood quite still, with his face towards me; and I can’t tell you how horrid he looked among the tulips and all those tall, gaudy, almost hothouse-looking flowers.  It looked as if we’d stuck up a waxwork instead of a statue in the centre of our garden.

“Yet almost the instant he saw me move in the window he turned and ran out of the garden by the back gate, which stood open and by which he had undoubtedly entered.  This renewed timidity on his part was so different from the impudence with which he had walked into the sea, that I felt vaguely comforted.  I fancied, perhaps, that he feared confronting Arthur more than I knew.  Anyhow, I settled down at last, and had a quiet dinner alone (for it was against the rules to disturb Arthur when he was rearranging the museum), and, my thoughts, a little released, fled to Philip and lost themselves, I suppose.  Anyhow, I was looking blankly, but rather pleasantly than otherwise, at another window, uncurtained, but by this time black as a slate with the final night-fall.  It seemed to me that something like a snail was on the outside of the window-pane.  But when I stared harder, it was more like a man’s thumb pressed on the pane; it had that curled look that a thumb has.  With my fear and courage re-awakened together, I rushed at the window and then recoiled with a strangled scream that any man but Arthur must have heard.

“For it was not a thumb, any more than it was a snail.  It was the tip of a crooked nose, crushed against the glass; it looked white with the pressure; and the staring face and eyes behind it were at first invisible and afterwards grey like a ghost.  I slammed the shutters together somehow, rushed up to my room and locked myself in.  But, even as I passed, I could swear I saw a second black window with something on it that was like a snail.

“It might be best to go to Arthur after all.  If the thing was crawling close all around the house like a cat, it might have purposes worse even than blackmail.  My brother might cast me out and curse me for ever, but he was a gentleman, and would defend me on the spot.  After ten minutes’ curious thinking, I went down, knocked on the door and then went in:  to see the last and worst sight.

“My brother’s chair was empty, and he was obviously out.  But the man with the crooked nose was sitting waiting for his return, with his hat still insolently on his head, and actually reading one of my brother’s books under my brother’s lamp.  His face was composed and occupied, but his nose-tip still had the air of being the most mobile part of his face, as if it had just turned from left to right like an elephant’s proboscis.  I had thought him poisonous enough while he was pursuing and watching me; but I think his unconsciousness of my presence was more frightful still.

“I think I screamed loud and long; but that doesn’t matter.  What I did next does matter:  I gave him all the money I had, including a good deal in paper which, though it was mine, I dare say I had no right to touch.  He went off at last, with hateful, tactful regrets all in long words; and I sat down, feeling ruined in every sense.  And yet I was saved that very night by a pure accident.  Arthur had gone off suddenly to London, as he so often did, for bargains; and returned, late but radiant, having nearly secured a treasure that was an added splendour even to the family Collection.  He was so resplendent that I was almost emboldened to confess the abstraction of the lesser gem -, but he bore down all other topics with his over-powering projects.  Because the bargain might still misfire any moment, he insisted on my packing at once and going up with him to lodgings he had already taken in Fulham, to be near the curio-shop in question.  Thus in spite of myself, I fled from my foe almost in the dead of night -but from Philip also....  My brother was often at the South Kensington Museum, and, in order to make some sort of secondary life for myself, I paid for a few lessons at the Art Schools.  I was coming back from them this evening, when I saw the abomination of desolation walking alive down the long straight street and the rest is as this gentleman has said.

“I’ve got only one thing to say.  I don’t deserve to be helped; and I don’t question or complain of my punishment; it is just, it ought to have happened.  But I still question, with bursting brains, how it can have happened.  Am I punished by miracle? or how can anyone but Philip and myself know I gave him a tiny coin in the middle of the sea?”

“It is an extraordinary problem,” admitted Flambeau.

“Not so extraordinary as the answer,” remarked Father Brown rather gloomily.  “Miss Carstairs, will you be at home if we call at your Fulham place in an hour and a half hence?”

The girl looked at him, and then rose and put her gloves on.  “Yes,” she said, “I’ll be there”; and almost instantly left the place.

That night the detective and the priest were still talking of the matter as they drew near the Fulham house, a tenement strangely mean even for a temporary residence of the Carstairs family.

“Of course the superficial, on reflection,” said Flambeau, “would think first of this Australian brother who’s been in trouble before, who’s come back so suddenly and who’s just the man to have shabby confederates.  But I can’t see how he can come into the thing by any process of thought, unless...”

“Well?” asked his companion patiently.

Flambeau lowered his voice.  “Unless the girl’s lover comes in, too, and he would be the blacker villain.  The Australian chap did know that Hawker wanted the coin.  But I can’t see how on earth he could know that Hawker had got it, unless Hawker signalled to him or his representative across the shore.”

“That is true,” assented the priest, with respect.

“Have you noted another thing?” went on Flambeau eagerly, “this Hawker hears his love insulted, but doesn’t strike till he’s got to the soft sand-hills, where he can be victor in a mere sham-fight.  If he’d struck amid rocks and sea, he might have hurt his ally.”

“That is true again,” said Father Brown, nodding.

“And now, take it from the start.  It lies between few people, but at least three.  You want one person for suicide; two people for murder; but at least three people for blackmail”

“Why?” asked the priest softly.

“Well, obviously,” cried his friend, “there must be one to be exposed; one to threaten exposure; and one at least whom exposure would horrify.”

After a long ruminant pause, the priest said:  “You miss a logical step.  Three persons are needed as ideas.  Only two are needed as agents.”

“What can you mean?” asked the other.

“Why shouldn’t a blackmailer,” asked Brown, in a low voice, “threaten his victim with himself?  Suppose a wife became a rigid teetotaller in order to frighten her husband into concealing his pub-frequenting, and then wrote him blackmailing letters in another hand, threatening to tell his wife!  Why shouldn’t it work?  Suppose a father forbade a son to gamble and then, following him in a good disguise, threatened the boy with his own sham paternal strictness!  Suppose -but, here we are, my friend.”

“My God!” cried Flambeau; “you don’t mean -”

An active figure ran down the steps of the house and showed under the golden lamplight the unmistakable head that resembled the Roman coin.  “Miss Carstairs,” said Hawker without ceremony, “wouldn’t go in till you came.”

“Well,” observed Brown confidently, “don’t you think it’s the best thing she can do to stop outside -with you to look after her?  You see, I rather guess you have guessed it all yourself.”

“Yes,” said the young man, in an undertone, “I guessed on the sands and now I know; that was why I let him fall soft.”

Taking a latchkey from the girl and the coin from Hawker, Flambeau let himself and his friend into the empty house and passed into the outer parlour.  It was empty of all occupants but one.  The man whom Father Brown had seen pass the tavern was standing against the wall as if at bay; unchanged, save that he had taken off his black coat and was wearing a brown dressing-gown.

“We have come,” said Father Brown politely, “to give back this coin to its owner.”  And he handed it to the man with the nose.

Flambeau’s eyes rolled.  “Is this man a coin-collector?” he asked.

“This man is Mr Arthur Carstairs,” said the priest positively, “and he is a coin-collector of a somewhat singular kind.”

The man changed colour so horribly that the crooked nose stood out on his face like a separate and comic thing.  He spoke, nevertheless, with a sort of despairing dignity.  “You shall see, then,” he said, “that I have not lost all the family qualities.”  And he turned suddenly and strode into an inner room, slamming the door.

“Stop him!” shouted Father Brown, bounding and half falling over a chair; and, after a wrench or two, Flambeau had the door open.  But it was too late.  In dead silence Flambeau strode across and telephoned for doctor and police.

An empty medicine bottle lay on the floor.  Across the table the body of the man in the brown dressing-gown lay amid his burst and gaping brown-paper parcels; out of which poured and rolled, not Roman, but very modern English coins.

The priest held up the bronze head of Cæsar.  “This,” he said, “was all that was left of the Carstairs Collection.”

After a silence he went on, with more than common gentleness:  “It was a cruel will his wicked father made, and you see he did resent it a little.  He hated the Roman money he had, and grew fonder of the real money denied him.  He not only sold the Collection bit by bit, but sank bit by bit to the basest ways of making money -even to blackmailing his own family in a disguise.  He blackmailed his brother from Australia for his little forgotten crime (that is why he took the cab to Wagga Wagga in Putney), he blackmailed his sister for the theft he alone could have noticed.  And that, by the way, is why she had that supernatural guess when he was away on the sand-dunes.  Mere figure and gait, however distant, are more likely to remind us of somebody than a well-made-up face quite close.”

There was another silence.  “Well,” growled the detective, “and so this great numismatist and coin-collector was nothing but a vulgar miser.”

“Is there so great a difference?” asked Father Brown, in the same strange, indulgent tone.  “What is there wrong about a miser that is not often as wrong about a collector?  What is wrong, except... thou shalt not make to thyself any graven image; thou shalt not bow down to them nor serve them, for I...but we must go and see how the poor young people are getting on.”

“I think,” said Flambeau, “that in spite of everything, they are probably getting on very well.”