It was in the autumn of 1918, when my medical practice was burgeoning on account of casualties from the recent war, when my friend Sherlock Holmes called upon me in the most unexpected circumstances. Loyal readers of the Strand magazine will, no doubt already be indoctrinated in such exploits of Holmes as the intrigue surrounding the Ruritanian Abdication Crisis. However, at that time Holmes had failed to uncover anything incomprehensible to the human mind for several weeks, and I was beginning to fear for his health.

I was conducting surgery on an elderly Major of Rifles who had lost a leg in the Egyptian campaign, and whom I was treating for scrofula of the stump, when I all of a sudden heard the ghostly, unexpected voice of my friend Holmes.

"I apologize for this peculiar method of gaining entry to your consulting rooms, Watson, but I must beg your company right away."

I looked up, behind me, and all about the room, but could see nowhere my one-time room-mate and companion. I stared at the laudanum bottle I had been about to hand over to my patient.

"The Major was otherwise disposed today, Watson", said the Major. "I have taken the liberty of taking his place. The streets are not safe for me to walk in my customary attire at present."

"But the leg, Holmes", I stammered. "How did you do the leg?"

"Ah, Watson", said Holmes in a voice of immensely pleased conceit, "you have been making the assumption all the time that I had two legs to begin with."

"But Holmes", I protested. "I have seen you run, and jump!"

"Have you, Watson? Have you really?"

"Are you, at present, engaged upon an investigation?"

"An investigation more brutal and savage, perhaps, than any other I have previously been involved in. I consider it normal to see a man's life taken from him by another for the pursuit of criminal gain, Watson; but it is rare indeed for him to be eaten afterwards."

Even I, who have been in Afghanistan, was appalled. "Surely not."

"Just so, Watson. In the past seven days, on Hampstead Heath, there have been seven attacks upon street musicians, each the player of a trombone of some description, and each attacked, if those who heard the attacks are to be believed, whilst executing the closing bars of Gustav Holst's Thaxted. In each case, the victim appears to have been attacked from above, the flesh crushed and cut, the bones splintered, the capital extremity entirely missing in many cases. Each victim's body was also notable for the stench of corruption which hung about it, like gas gangrene."

"Accidental death has been ruled out, then? A recurrent trombone malfunction of some order-"

"- has already been checked for. The instruments were produced by different manufacturers, all of the very highest reputation and with large portfolios of quite living, healthy customers. However, I do not trust the unmedical minds of London's Metropolitan Police, Watson. I require your keen anatomical brain. A fresh body has been discovered on the Heath this very hour. I enjoin you to take the new-fangled subterranean railway to Hampstead. I will be waiting outside the station, though of course you will not know me."

The London fog was thick as wool pulled over the eyes when I stepped out of the station at the pleasant rustic hamlet of Hampstead. Streetlamps were already being lit, each surrounded by a saintly halo in the murk. I bought a paper from a decrepit scion of the lower classes and sat down on a bench to wait for my tardy associate.

"Watson!" hissed a voice through the gloom.

"Egad" I replied. "Where are you, Holmes?"

"I have just sold you a copy of the London Evening Standard. LATEST NEWS, GUVNOR! Though I had thought you might have remarked on my trombone."

I remarked on his trombone. "Good lord, Holmes! You have a trombone. Are you mad?"

"Not in the least. This is quite a singular trombone. It was discovered, twenty feet up in the branches of a tree, but otherwise almost entirely unharmed, a hundred yards from the body of the penultimate victim. It plays beautifully." He essayed a bar of Thaxted.

"An improvement on your violin, at any rate. And now, where is the last man to be murdered?"

Holmes led me with the accuracy of a homing pigeon through a white haze out of which trees drifted like gigantic submarine fauna. Finally, he came upon a spot where two policemen sat playing cards over the sad, torn body of one of our city�s street musicians.

"Evening, Mr. 'Olmes", they chorused.

"Good evening, officers. Now, Watson, your medical training will almost certainly draw your attention to the body�s non-possession of a head. What I wish to know is, what removed that head so swiftly and so irrevocably?"

I examined the poor corpse as thoroughly as I could. "I have seen something similar to this at only one point in my career", I said. "An Indian mugger, not a man but a crocodile, which caused a commotion in our billet in Peshawar. One night, one of our subalterns, answering the call of nature by the waterside, was seized about a part of his anatomy I dread to name by the scaly abomination. Sixteen rifle bullets were needed to kill it, by which time the unfortunate officer was long dead. The brutes have jaws capable of cracking a man�s ribcage like an egg.

"Interesting. And what do you suppose did this?"

"Something, I would hazard a guess", I said, "with bigger jaws."

Holmes was striding out across the frozen grass, tapping his heel with his cane impatiently. "So, what do you suppose has bigger jaws than a crocodile?"

"I have no idea. An extraordinarily large lion escaped from a zoo, perhaps."

"Come here, Watson."

I walked closer. Holmes was standing over something, an impression in the turf.

"There. What do you imagine that is?"

I looked. Then, I stared.

"It's a footprint, Watson", said Holmes. "It is the footprint of a gigantic ten thousand pound theropod from Hell."

Ten minutes later I was staring at Homes as though he were the starkest madman.

"A megalosaurus?"

"The very same. You know my maxim - when you have eliminated the impossible, whatever remains, however improbable, must be, etcetera, etcetera."

I began to feel somewhat light-headed. "Holmes, the megalosaurus has been extinct for nearly two hundred million years."

"Not so, Watson." At this point Holmes fished out a stack of books and papers he had been concealing in his trombone case and began flicking frantically through a periodical. "I considered all the animals that currently exist in the world and are capable of killing a man, and eliminated them one by one from my inquiries. The leopard lacked the sheer height to attack from above unless concealed in a tree, and I could find no claw marks in the bark of any tree hereabouts. The elephant, meanwhile, whilst possessing sufficient elevation, would gore or trample in preference to biting. Finally, I concluded that the attacker was an animal unrecognized by conventional zoology.

Therefore I switched from zoology to palaeontology. The characteristic dual puncture wounds of a sabre-toothed tiger attack were not present, nor were the sixfold blunt contusions that would indicate a charging uintatherium. I went through ten heavy tomes at the British Museum before I alighted on my culprit. A megalosaurus had performed this crime, Watson - a huge Jurassic beast moving on powerful three-clawed feet and with a mouth like a cavern of stalactites. I know what you will say, Watson - nowhere on Earth does a megalosaurus currently exist. But there are reports from the Belgian Congo of creatures that resemble a stegosaurus more than a stegosaurus's maiden aunt, and in addition, there are the remarkable accounts which I now commend to you." He had now found the pages he had been looking for, and set to reading aloud enthusiastically.

"Proceedings of the London Zoological Institute, June 13th, 1917: an address to be delivered by Professor Challenger to a general assembly of all members, regarding extraordinary discoveries recently made in a high tributary of the Amazon�"

"That was all poppycock. Totally discredited. The expedition brought back no evidence of the existence of living dinosauria in the Amazon whatsover."

"You must remember, Watson, that the generally accepted public account of the expedition is that of Mr. Edward Malone of the Daily Gazette", admonished Holmes. "But I have recently been across the Channel to purchase Professor Challenger's own version of events and it makes most enlightening reading. As you know, the Professor's account was savaged by Her Majesty's censors, only a few select copies making their way here across the Channel after having had to be published in France."

He switched to a different volume, this one hardbound and bearing a lurid cover engraving of a lady in night attire being improbably menaced by a tumescent Mesozoic reptile.

"September 13th, 1916. Violently, bestially drunk on that fermented mash of giant spiders the natives call ghula-ghula. Still see huge green dinosaurs everywhere. Am having to gradually force myself to face the horrid truth that they might actually be real. After tea, with Roxton, Malone and Summerlee out of the camp, disported myself with two of the hallucinatory Stone Age women hereabouts, enjoying to the full their supple and surprisingly real-seeming honey-coloured bodies -"

"That is quite enough, Holmes", I snapped. "The ravings of a man in an arachnolysin-induced delirium are hardly proof of the continued existence of dinosaurs."

"Agreed, Watson. But if we read on! If we but read on! December 1, 1916. Our return to England has been safely negotiated without either my confederates or Customs & Excise suspecting I had more in my baggage than declared. The egg is ovoid - as is only to be expected - about the size of a large coconut, porous skinned, and a bright saffron yellow in colour. I have been incubating it by stealing into the cargo hold and covering it with rotting kitchen waste, and in addition, whenever possible, sit on the egg personally. When questioned why I was sitting in rotting kitchen waste in the cargo hold by the ship's purser, I simply replied that I was incubating an egg which, when it hatched out, would develop into a twenty foot long maneating lizard, whereupon he simply grinned, tapped his cap in a friendly way, and left me to my own devices.

"February 2, 1917. My hatchling has arrived. Have been feeding it turkey giblets, which it consumes with gusto. Have named it Gladys, after Malone's carnivorous reptilian fianc�e. Gladys very attracted to bright objects and movement. Already appear to have lost the cat, a huge fluffy useless article good only for destroying valuable furnishings. Wife distraught. Am beginning to like Gladys already.

"April 10. Gladys over six feet long now. Intend to take her in to one of that confounded bore Walton's lectures on the malleability of germ plasm. I will say nothing and announce nothing - just take her in on the end of a long piece of string, and sit at the back, and stare. Then let that pieheaded buffoon deny the existence of living palaeozoons.

Green, the children's music teacher, has packed his things and left. Complained about having to deliver lessons in the same room as Gladys; claims music drives her into a bestial fury. Good riddance, for his music drives me into just such a fury, as he practises nothing but Holst's Jupiter at every hour of the day and night.

"To the point, Holmes."

"September 23. Have negotiated a regular meat supply for Gladys from a Mr. Glass, a heavily bearded importer of fine Irish beef. Have surveyed Mr. Glass's warehouse and suspect his beef was formerly in the habit of whinnying, but his prices are cheap. Two of his associates delivered the first consignment to our drawing room, where Gladys is currently residing. The impertinent lackeys passed doubt on the ability of the window bars to prevent Gladys from escaping. Was only too ready to demonstrate to them how the windows could only be opened on the outside.

"September 25. Donned diver's helmet and steel gauntlets and took half horse carcass in to Gladys as a treat. Disaster! Window open, drawing room empty, three-toed clawprints disappearing over the lawn into the distance."

Holmes snapped the book shut.

"Are you seriously suggesting that a palaeozoic carnivore is stalking Hampstead Heath?"

"I have been checking public records,Watson. There have been over fifteen cases of unexplained decapitations and disappearing animals on and around the Heath in the last twelve months. The police no doubt failed to connect them with this investigation due to the fact that none of them involved trombones."

"So a prehistoric monster is responsible for these killings?"

"Not entirely, Watson. There are still facets of the affair that elude me. For example, in all six cases, listeners reported that the trombonist's solo was accompanied by a lone fiddle part which joined the refrain just before the notes suddenly, tragically choked off. No, my friend - I am thinking that the mind behind these enormities evolved quite recently."

Several days later, the eternal fog still covered the city. I was treating a case of phossie-jaw in a middle-aged match worker. My signature was still wet on the prescription for morphia when the worker suddenly spoke up - quite impossible in a patient whose jaw had entirely dissolved into a sort of calcareous mush - taking me momentarily aback.

"Good morning, Watson."

This time, however, I regained control with a steely resolve. I did not even look up.

"Good day, Holmes. I hope you realize you have just wasted fifteen minutes' valuable consulting time."

"I do apologize, dear fellow. The streets remain dangerous, and I had to see you. It was the excitement of finishing a case that has been puzzling me for some time."

"The Hampstead trombonist decapitations?"

"The very same. I have found what I believe to be an answer, Watson, in forensic palaeontology." Holmes fidgeted in his chair nervously. "Don't you want to know how I feigned a jaw entirely dissolved by phosphor poisoning?"

"I most certainly do not."

"Very well. It is a case, Watson, that will go down in the annals of all cases in which a dinosaur was used as a murder weapon. For there is a human being behind these deeds, Watson, make no mistake of it." Out of a carpet bag on the floor he drew another volume of bound periodicals. "These are the observations of a Mr. Barnum Brown, who has recently discovered a colossal ornithopod in the fastnesses of Alberta which he names Corythosaurus Casuarius. This creature, a member of the hadrosauridae or duck-billed dinosaurs, possesses a singular crest on its skull - a hollow, air-filled bony structure which some palaeontologists have wrongly supposed to have been used for breathing while the animal snorkelled like a scaly submarine. There is, however, a slight drawback to this theory in that the crest possesses no exterior nostril �"

"The murders, Holmes."

"Ah, yes. There is, you see, Watson, a school of thought who believe the crest formed a sort of resonating chamber with which the beast would be capable of making distinct musical notes - not unlike, one would imagine, a trombone."

"Holmes, I cannot see any conceivable reason why a house-sized prehistoric creature would wish to make a noise like a trombone."

"These creatures were not the sharpest of sorts, Watson. Some of them needed secondary brains in their abdominal regions to remain capable of coordinating their movements. It is also true that large creatures do not necessarily have acute senses; the rhinoceros is notoriously short-sighted, and relies on its sharper sense of hearing to detect approaching hunters.

"Consider, then, a herd of such creatures. Like African herbivores, they might not all be members of the same species. Multiple species of African antelope often gather at the same water-hole to drink. However, our antelope weigh five tons and are only marginally cleverer than the pond scum they are lapping up. It is quite possible that they might elect to mate with the wrong species if they are not provided with some constant audible cue. Some species of hadrosaur might therefore have made noises like trombones, as if to say, Here I am! I am a trombone-crested hadrosaur, and other trombone-crested hadrosaurs may profitably choose to mate with me. But the noises they made would not be of interest solely to their mates. They might also have interested their predators."

"Good God, Holmes", I cried. "Are you telling me those poor wretches died simply because their instruments made sounds resembling that creature's natural prey?"

"I not only believe it", said Holmes, "I intend to prove it, by the most direct means possible."

He drew out the trombone from his bag, along with a copy of the sheet music for Thaxted.

***

"You will not need your pistol, Watson. It would be entirely useless against the creature. Shooting it accurately in the brain would be as hard as hitting a bull from a hundred yards, and I imagine even four-five-five ball would simply bounce off its scaly hide."

We were walking through a wilderness of winter-deadened trees, in a fog in which an entire herd of hadrosauridae could have stood shoulder to shoulder unobserved. A bandstand loomed out of the murk. Posters announced a forthcoming event involving royalty.

"There do not seem to be any dinosaurs in the vicinity, Holmes. I feel sure that such large animals would advertise their presence."

"A predator", said Holmes, "never advertises its presence." And he raised the trombone to his lips, and blew out the final bar of Thaxted. A tear rose to my eye at the thought of the country all of whose ways are gentleness, all of whose paths are peace.

Then the hairs at the back of my neck stood on end as I heard a distant, clumsy crashing from far away in the fog, as if a drunken coachman were attempting to drive an omnibus through heavy brush.

"The hunter's afoot", said Holmes. "And it is we who are the game." He motioned to me to follow as he stole away.

"Confound it, Holmes! I hadn't expected your damnable theory to actually be correct!"

"My theories, Watson, are always correct." With that, he plunged into a nearby drain or ha-ha and squelched ponderously along it, not appearing in any hurry to get to the other side. "Into the water, Watson. In this fog the beast will hunt by scent."

I have no shame in relating that I piled into the water more smartly than I have ever piled into water before, particularly since I heard, at a somewhat lesser distance now, the immense crackling whisper of something dreadfully, fearfully heavy walking across the carpet of fallen leaves on the Heath towards our former position. Walking slowly, and appearing to deviate to left and right, like a questing hound. I believe I actually heard breath, escaping like a head of steam from a ship's boiler.

"Do not make a sound, Watson, for your life depends on it."

Holmes claims that he still saw nothing at that point - I would have been able to see nothing even had the beast been standing right next to me, for I had my eyes tight shut. But at that point, we heard another sound, deep and sonorous, singing out through the fog - the sound of the low notes of a violin. It is difficult to convey how I knew purely from the sounds I heard through the mist that a Mesozoic lizard was cocking its head on one side, but somehow I knew this was what was happening, as if a bird on a branch had heard another bird whistle, or a dog heard its owner call.

We heard it plunge away through the fog.

"As I suspected", said Holmes. "There are two hadrosaur species."

We sat in the pleasant surroundings of the Jack Straw's Castle inn near the flagstaff on the northern perimeter of the Heath. Warm beer was a welcome antidote to the cold.

"I cannot understand, Holmes, how the fact that there were two species of hadrosauriwhatsit can possibly be significant."

"Quite simple, I imagine. The first species, whose calls sound like those of a trombonist executing the final bars of Thaxted, are our megalosaurus's preferred prey. The second species, meanwhile, whose call is more violinlike, are a related animal which moves with the herds of the first. But our carnivore will not attack this second species."

"It will not?"

"I will stake my life on it. These animals are not prey. Their flesh is shunned by our megalosaurus, which will nevertheless follow them in much the same way a lion will follow an animal it is incapable of bringing down, such as a rhinoceros, in the hope of finding other herbivores it can bring down. Nevertheless, Watson, whoever is controlling this creature is playing fiddle with the Devil. And he is about to walk through that door, right about - now."

The doors opened to admit a shabby-looking street musician, similar in appearance to the poor devil I had examined only a day earlier.

"Mr. Green, I believe", said Holmes. "Formerly music teacher to the family of Professor Challenger of Enmore Park. No, don't trouble yourself to pull out that revolver. You will find that almost every person in this hostelry right now is an armed member of Her Majesty's Metropolitan Police."

Eerily, as if Holmes were some macabre puppeteer, every single one of the establishment's customers turned round and raised their hats to the newcomer.

"You will perhaps be mystified as to how I know your name. You are, of course, an adherent of the Fenian cause and a proponent of Home Rule for Ireland. The merits or demerits of that question I leave to politicians. I involve myself only at the point when people believe their political causes justify murder. Your principal mistake was in presenting yourself, in disguise, to your former employer as a meat wholesaler of the name of Glass. 'Glas', as Watson doubtless does not know but I certainly do, is the Gaelic for Green, a childish conceit which led to your downfall. You noticed several months ago whilst tutoring Professor Challenger's children that the notes of the trombone appeared to induce a blind killing rage in the juvenile megalosaurus chained up at the other end of the drawing room. The notes of the violin, meanwhile, served only to attract its attention and cause it to follow the violinist round the room. It was after learning these facts that you formulated your plan.

You planned to remove the beast from confinement using two of your Fenian confederates, and train it to attack human beings. The small number of bites inflicted on his serving staff had convinced Challenger that the creature did not seek out human beings as prey; it needed to be taught to do so. And you, Mr. Green, have been teaching it to kill for the last twelve months. And why have you been doing so? Why, in only one week's time, His Majesty King George is due to attend an open air concert at the Parliament Hill bandstand on the Heath, where the final piece on the programme will be Mr. Spring-Rice's inspired lyrics to Thaxted by Gustav Holst. In fact, it is only the final note of that tune that sets off the beast, am I right?" Holmes began whistling the final few bars of Thaxted.

The musician�s face palled.

"For pity�s sake," he exclaimed, in a pronounced Dublin brogue, "you do not know what you�re doing. "If you value your life, if you value all our lives, stop!"

And Holmes did stop, drawing out that long penultimate note, and laughed. "Indeed", he chuckled. "How could it be otherwise? We have Professor Challenger's word that you practised Holst's Jupiter in the beast's presence without ill effect. Jupiter, of course, would have been safe to practise, for in Jupiter, which is otherwise identical to Thaxted, the final note never resolves. Were you, perhaps, hoping that the beast would wreak such havoc among the crowd that His Majesty would be trampled?"

The scarlet-haired Fenian shook his head. "You do me an injustice, sir. If you had only troubled to look further into the cast of the orchestra, you would have discovered I was to play the principal trombone. I intended to place myself directly before the monarch of your despicable island, blowing my horn for all I was worth. The beast would surely have taken the ermine-laden buffoon after it had finished with me."

Holmes nodded. "I see you are a man of courage, if a misguided one. I am offering you an honourable way out."

He extended a hand, proferring the trombone. The Irishman nodded sadly and accepted it. Holmes picked up the untouched pint of ale he had been nursing since we arrived, and held it up as well.

"A last drink for a condemned man."

Green accepted the pint, and drained it with gusto. Then, he turned round to the assembled police officers and cried:

"Fianna Fail!"

- before striding out through the inn doors into the white murk. We saw no more of him; but heard, droning in from without, the clear, calm notes of that timeless patriotic hymn which, I became more acutely aware than ever before, apply to any country, any King, and more especially to that great country we all hope to become citizens of upon our end.

Then, suddenly, there was a great thundering crash, and a hideous roaring, and the notes of the trombone ceased as the instrument itself was flung out of the fog, bent double, towards the window where we sat.

"Gods, what a beast! It will take a troop of soldiers with an artillery piece to kill it!"

"I think not", said Holmes. "That pint of ale contained enough strychnine to kill ten elephants. Now, I believe there is time for me to consume another less dangerous pint before we repair to the bandstand, where I believe the local brass ensemble is currently setting up to practise. I fancy I could stand to hear that tune again."

And he clicked his fingers for the barman to bring him another beer.

Author's Notes

Dominic Green has written several short stories for Interzone magazine, often in a satirical vein. His story Send Me a Mentagram was picked for the prestigious Year's Best Science Fiction anthology in 2003.

Here's what Dominic had to say about this story.

Conan Doyle was the Michael Crichton of his time - someone who wasn't 'a science fiction writer' or 'a crime writer', but a man who was capable of reeling off both the Sherlock Holmes stories and the Professor Challenger series, and seeing no problems of genre conflict in doing so.

Conan Doyle wrote what he felt would entertain his audience, much in the same way as Dickens or Shakespeare - also, it has to be said, in the same way as H.G. Wells, allegedly the Big Huge Man of Science Fiction, who also wrote a good deal of mainstream material. I am, I suppose, nominally a science fiction writer, but I see the genre as being a licence to write anything I damn well please rather than a constraint to confine myself to depicting taut-thewed Lenspersons of the Galactic Patrol.

I've always liked the Victorian era for its sheer preposterousness - a century where table legs are clothed decently, but child prostitution output struggles to meet popular demand. It's a century which is deceptively familiar - nineteenth century English is much the same as today's, after all, and the men have the common decency to run around in trousers - but also more alien than the far side of the Moon. Opium is a common analgesic to which vast swathes of the population are addicted. People have front parlours which they never use except on special occasions. Small squares of fabric are placed on the backs of sofas to prevent the massive quantities of oil gentlemen plaster their barnets with from damaging the furniture. It's a strange, strange world back then, people. Better pack your space suit.