I was still in the Lake District when I heard that the annual Market was to be held in Hull. I've said before that the Black Market doesn't exist in any one place alone. This is true: it is a concept in aggregate, an abstract collective of mercantile bodies who stake their claim to a particular territory or wander aimlessly across the country. All of them seeking out the next big opportunity.

But every once in a while, the Black Market comes to town, and this is the biggest opportunity of them all. There's a very childish excitement that surrounds the event, as may be expected of a massive underworld party, and of course it's the only chance we get to show off to all our peers. Vendors of otherworldly goods will flock from miles around for the chance to be noticed by new customers – and to one-up their competitors. It's the only time you'll find so many of us in one place, and it only happens once a year.

No one really knows how it happens, either. The word simply spreads among vendors up and down the country that the Market is being held; the time and location will be passed along like a hot but sweet potato.

I don't know who decides on these details. Maybe nobody decides. It has crossed my mind more than once that the Market is so loaded with magic and occult power that maybe, in a disturbing sort of way, it might be alive. Maybe we are all tendrils of this great amorphous beast stretching across the country, like the tentacles of some immense preternatural octopus. And once a year it pulls us all inwards to feed on the things we've gathered. Or maybe it's like a colossal, slow heartbeat, pulsing outwards and inwards to the tune of the seasons.

But that's just my fancy. I have a lot of time to think to myself during those long car journeys.

"Why we gotta go all this way just for a market, gwas?"

Car journeys have been less peaceful of late.

"It's only three hours, Ang. And it's not just any market. It's the market."

The coblyn dropped her greasy pie paper in the footwell, where her dangling feet were just beginning to brush the top of a rising layer of garbage. If she slipped off the seat I was sure she would drown in it.

"Ye should do somethin' about this rubbish," she said, as if reading my thoughts.

"I'm not your housekeeper."

"Tis your car."

"It's your mess."

"Your problem."

I changed gear somewhat roughly, then winced at the resulting crunch. I shouldn't take out my frustration on the old girl. My car that is, not Ang.

"Have you ever considered that you should try to pull your weight around here? This isn't a free ride, you know."

"Nope." She leaned back and tipped her flat cap over her eyes. "I already paid."

We'd had this conversation a dozen times or more, and I already knew how it ended: Ang would berate me for not yet having found any information on her missing coblynau brethren, and then she would helpfully remind me that I had lost most of her prized bluecaps to a thief, and then I would stuff another pasty in her mouth just to shut her up.

But, for once, I had a counter argument.

"Let me tell you why you should be interested in this Market, Ang," I said. There was a disgruntled noise from under the flat cap. "Once a year, for three days, everyone who's anyone attends the Market."

"And you're 'anyone', are ye?"

"Only the finest purveyor of occult goods in all of England!"

"Aye. I read yer business cards. Twpsyn."

"My point, Ang, is that the annual Market is the biggest melting pot of otherworldly citizens you will ever come across. For just three days a year we're not hiding in shadows or keeping our heads low. We're big and loud and we love to talk. Imagine a host of intrepid travellers swapping their tales of victory and encounters with the unknown! Everyone's bragging about their biggest sales, their newest finds, and possibly about weird new species they've met."

"Ye better not be callin' me a weird specie," Ang grumbled.

"I swear you miss the point on purpose. Ang, your kind aren't exactly common in the world any more, y'know? We don't even see knockers that much these days –" she bristled at the word knockers,"– so I'm convinced that if anyone's come across a coblyn in their travels, this is where we'll hear about it. Heck, maybe your friends will come to the Market themselves. There's always something that we've never seen before; maybe coblynau will be the next big thing."

This is perhaps the most honest guarantee I have ever given. It is a foregone conclusion that at each big market there will be something you've never seen before. It might be some precious, mythic artefact (last year there was a furore over the bones of a lost saint), or some new type of tincture (love potions and youth tonics are old hat), or maybe some bizarre creature scarcely caged (although this often ends horribly – the imbecile who introduced us to piskies ought to be shot).

My mind had been racing for weeks over the prospect of what the Hull Market would bring. And what I, in turn, would bring to it.

Ever since I met Ang a couple of months ago, I'd been euphoric with the knowledge that I now possessed six bluecaps: fiery spirits usually seen only in the hands of knockers and other mine-dwelling goblins. Knockers and coblynau don't part with these things easily – bluecaps are, after all, the spirits of their ancestors. So I was understandably aching with anticipation for the opportune moment to show off my amazing catch. I, Jack Hansard, had bluecaps for sale, which is something that no other trader could boast.

Or a tleast, now I had bluecap.

Blast that thief. One moment of distraction, and I'd lost the biggest opportunity of my life to some woman with a nice smile and quiet eyes. Her eyes, I couldn't get them out of my head.

We recovered just one of the stolen bluecaps by luck more than anything else. Ang would never let me forget it.

So now I had one bluecap to sell, which was substantially less exciting than six bluecaps. Ang still had the one in her lantern, but she wasn't letting go of it for love nor money. Still, one bluecap was better than none, and it was worth smiling about. I've decided that I'm going to make some waves this year.

***

When we arrived in Hull, it was well past midnight. Just as well, because the Market doesn't open its doors to anyone before the twelfth hour. Sort of traditional, you know.

We pulled up at a warehouse on the river front. An innocuous, blocky building nested in a cluster of identical warehouses, it was the perfect venue for a three-day gathering of the country's underworld.

Now we just had to find the door.

As we circled the building, I concentrated on unfocusing myself. The trick is to become as fuzzy as the hidden door – to slide into the same space it occupies. I could feel the edges of it as we drew closer.

"What are ye waiting for?" said Ang, giving me a curious look. "Door's right here, gwas."

"One moment," I mumbled, gritting my teeth with the effort of concentration. The wall in front of me shimmered, and within a blink it was a door, as it always had been.

"You got rubbish eyesight, gwas," Ang said, shaking her head.

"It's a human thing. You ready for this?"

"Aye."

I pushed open the small door and was hit by a crashing surge of noise. Ang followed, dumbfounded, as she took in the vast crowds swarming between rows upon rows of traders.

I grinned like I was home. "Welcome to the Black Market."

I hefted my bags over one shoulder and grabbed the fold-up table, armed and ready to claim a small square of this bustling territory as my own. The warehouse had appeared small on the outside; on the inside it was palatial, just like that alien doctor's time travelling spaceship thing (I've never really watched television). Around the edges of the room there was a thriving trade in comfort where a few bars, eateries, and bunks-for-rent had set up shop: not everyone is as happy to sleep in their car as I am, and a thin mattress with a pillow full of rocks is better than a kick in the teeth.

The rest of the hall was taken up by the chaos of the Market. I leaned down to Ang:

"Try not to smile at the people you pass. And try to ignore the ones who don't look like people."

She nodded mutely and followed my weaving trail.

The centre was where I wanted to be, in the very hub of all that commotion. It sucks people inwards like a black hole, so all the best stuff is found in the very middle. I've never had a spot even close to it.

Today would be the same.I'd have to be content with my humble pitch on the end of an outer row. Table out, curtains up, let's put on a show.

"Ang, pass up those bottles, will you?" I looked around for the little nuisance. "Ang?"

She poked her head out from under the table, large ears quivering. The noise around us was thunderous with the stamping of boots, humming of voices and clinking of coins.

"You're not going to hide down there, are you?" I said, a little surprised. It wasn't like her at all, she was usually so brash and full of herself. I normally have trouble convincing her to keep a low profile when we're out on the streets. Then it occurred to me that Ang has only dealt with humans before, and she's used to lording it over them.

Men would both fear and revere coblynau in the mines, leaving out food to ensure their continued affability. But at the Market you had to pay attention to the shape of your customer, and many of them were pretty monstrous.

There was at least one lumbering troll in the crowd. Granted, it was on a leash, but that was no less reason to be worried about it. There were plenty of figures that looked human-shaped at first glance, but out of the corner of your eye you'd see the flick of a cow tail, the glint of much-too-sharp teeth, or perhaps it would be the stench of rotten meat that gave them away.

"C'mon, Ang. Work to be done, eh?"

She nodded reluctantly and began passing up stock to the table. "You know many people here, gwas?"

"Oh, plenty," I said, modestly. "Been building up my contacts. You've got to know who's who in this business."

"Who's 'im, then?" she asked, pointing at the trader across from us. He had no table: instead a stack of glass tanks filled with murky water and suspicious seaweed made up his pitch.

"That's Tony Gill," I replied. "Deals in aquatic... creatures."

"'E looks slimy. And 'e stinks o' fish."

"He catches them himself."

A similarly slimy customer approached Gill's stall. Ang watched in rapt fascination as the two conversed before exchanging currency and handshakes; she flinched as the customer stuck his head deep into one of the tanks. The water gurgled, and the man emerged with a splash. Three flailing tentacles were briefly visible before they were sucked into his mouth. If you looked too closely you could see movement under the bulging skin of his throat.

Ang looked too closely.

"Try not to throw up on anything valuable," I said. I didn't bother hiding my grin as I went back to arranging my table. Pride of place would go to the bluecap, my big score. But I'd wait awhile first, build up a crowd – and then a big reveal. Waves, I tell you!

"Hansard! How do, mate!"

My hand was gripped in the firm handshake of one surprisingly tanned Irishman.

"Tracey!" I responded,warmly. "Didn't know you were back over here, good to see you in one piece. How was the continent?"

"Full of competition." He grimaced. "Got a few more songs in my belt, for what it's worth. Not much call for a traditional siren these days, you know? Too many of my kind have packed it in for bloody pop stardom."

"Can't say I blame them," I mused. "Who wouldn't want a life of fame and fortune?"

"Someone who doesn't want to be hunted down for singing people to death," he said, wryly. Fair point. Can't say I envied his situation.

Ang re-emerged looking a little less green and began digging around the bags for a stray pasty.

"Who's the kid?" exclaimed Tracey. "Don't tell me you've picked up some foundling?"

Ang turned her wizened face on him, her gaze chilly and unimpressed. Tracey took a step back and gave an uneasy smile. "Hey now, didn't mean any harm. Didn't realise you were a knocker, that's all."

I stepped between them as fire lit up Ang's eyes.

"You see, it's–"

"Not knocker."

"–a bit tricky because–"

"Nor knacker."

"–she doesn't–"

"Coblyn, I am!"

"–like that word," I finished lamely. I leaned closer in a conspirational manner. "Between you and me, she's given me my biggest score ever. She can call herself what she wants."

Tracey's stunned expression twisted into amusement. "What score would this be? You've never had a good sale as long as I've known you."

"All shall be revealed in good time." I knew I sounded smug. I didn't care; I was enjoying myself too much.

"You sure you're not going to reveal yourself to be an utter prat?"

"You have so little faith."

"Well, it wouldn't be the first time."

Ang popped up between us. "Thought you said ye were some kind o' big man here, gwas?"she said, raising an eyebrow.

"I am! Or, I will be. Soon. Very soon."

Tracey shook his head disparagingly. "Your problem, Hansard, is that you don't have a niche. Just look at this mishmash of crap you're selling." He waved his hand at my entire pitch.

"You're wrong there," I said. "I've tried lots of niches."

"I mean you need to have a niche for more than five minutes."

"Ye do seem t'get bored o' things real quick," said Ang.

"Oh, shut up, both of you."

"You ain't really anything here, are ye?" she continued. "Tupenny merchant of tat is what you are. 'Anyone who's anyone', my arse!"

"Why don't you take a walk!" I spat. "Go and eat somebody else's food for five fucking minutes!"

Despite the incessant roar from the throngs of people milling around us, it was like a little bubble of silence had bloomed in our tiny circle.

"Don't like swearin', gwas," said Ang, slowly. I suddenly found myself recalling the old stories of rocks inexplicably falling on miners' heads when they were rude to the spirits of the mine. I tried not to instinctively duck.

Ang readjusted her cap over her dishevelled curls, picked up her lantern, gave me a final unforgiving look, and disappeared into the crowd.

"Looks like you're in the dog house," murmured Tracey.

"Pretty sure I've been living there for the past month," I said, gloomily.

"Drink?"

"Ought to sell something first. Anyway, there's my big reveal. I'm not joking, you know."

"Of course you're not," he replied, with more than an ounce of pity in his voice.

"Shouldn't you be working?" I said, irritably. "Singing happiness at people and what-not?"

"Just browsing. I'll earn my living later." He broke off, distracted by a group of women perusing my stall. "Ladies," he said, in his most charming voice (which, for a siren, is about as charming as you can get).

They flashed large, dark eyes at him and batted their ridiculously long lashes. They had a barely-there, waif-like quality about them. The tallest of the three picked out a ring from my table and offered it forward. In a rich, breathy voice she said: "How much for this?"

"A kiss and it's yours, fine lady," said Tracey, stealing my cue.

She twirled mossy hair in her fingers. "Surely not enough for such a pretty thing." She paused, lips parted, pink and inviting. I looked on, bored. "Perhaps I give you a better price?" she said, with a deep sigh that sounded like the wind.

"I would be honoured to... barter, with you," said Tracey. He bowed, like the ludicrous poseur he was. "Devin Tracey, at your service, fine lady."

She giggled and held out a beckoning hand. I pulled Tracey back and whispered in his ear:

"You saw she's a huldra, right?"

"Of course. How could I resist something like that?"

"Cow tails turn me off."

"Your loss."

"I heard their backs are covered in tree bark as well."

"How about I tell you later?"

I watched him saunter after the seductress and her companions, unsure whether I should be envious or not. I can't say I've experimented much in the non-human area of the bedroom. Too much chance of something weird or painful happening to your valuables, if you catch my meaning.

Now that all the distractions were gone, I could finally turn my full attention to sales. I was just launching into my patter when I heard the commotion.

I would have thought nothing of it, if it weren't for the screeching Welsh insults that punctuated the uproar.

I groaned and vacated my pitch, then fought my way through the rabble (which was quickly turning into a mob at the prospect of a fight) towards the source of the ruckus near the centre of the market. As I leapt over the last table (and the shoulders of an angry Sandman) I found Ang ferociously grappling with two men trying to hold her down.

"Basdun!" she screamed. "Give them back!"

"Hold it!" I shouted, just as one man raised a club, ready to crack Ang upside her head. I ran in, half-tripping over my coat in the process, hands held out placatingly. "Hey now, what's she done, eh? No need for this, she'll be quiet– Ang. Ang! Ang. Be quiet." She shut up long enough for one of her assailants to answer me.

"Caught the little goblin stealin' shit," he said. "You know the rules. Hands to y'self."

"I'm sure there's been a misunderstanding here," I assured. "Ang isn't the thieving type, honestly."

"He's got my bluecaps! That basdun has my bluecaps!"

"What?" I looked round, dumbfounded. Sure enough, there were five bottled bluecaps sitting proudly on a table not three feet from me.

"Whose bluecaps?" said another voice. This one I recognised; it was almost as charming as Tracey's, and it made me want to punch it repeatedly. Its owner ambled forwards and leaned down to stare into Ang's eyes. He smiled condescendingly. "My dear, these are not your bluecaps. You see, they are in my possession. That makes them my bluecaps."

"You thieving basdun! Ceri grafu!"

He straightened and turned to me. "Is this lad with you, Hansard? You should teach him better manners."

I clenched my jaw, politely refraining from knocking the smug smile off Edric Mercer's face. I cannot express how much I hate this man. He wears this stupid, long leather coat. I bet he thinks it makes him look cool. I also wear a long coat, but mine is completely practical and necessary for my work: I'd be nothing without all these pockets. And he has a hat. Big floppy thing with a wide brim and a feather in it. A feather, for goodness' sake.

"Where did you happen to acquire those bluecaps?" I asked, biting back the insult my mouth was begging to tack on the end.

The smug bastard tapped the side of his nose and smirked. "You know how it is, Hansard, can't go revealing tricks of the trade."

"Tricks like stealing from other traders, you mean?"

He merely smiled and waved graciously at his two lackeys. "You can let the little one up. I hardly think we need to fear such a small menace."

I managed to grab hold of Ang before she could lunge for Mercer's knees.

"You should keep an eye on him," Edric continued. "Wouldn't want any more... misunderstandings. Such things can be fatal, you know."

"Indeed." I squared my shoulders. "I'd hate for you to be implicated in a similar kind of... misunderstanding."

I moved to leave, but he placed a hand on my shoulder and murmured: "You should watch your back in this pond, Hansard. You're such a little fish." He smiled again and turned away.

Bastard. Has to have the last word.

"Why are we leavin'?" hissed Ang. "We need to get them bluecaps back!"

"Are you nuts? They string people up for thievery around here."

"He's the one should be strung up."

"Can't say I disagree. Are you certain those bluecaps were yours?"

Despite being so much shorter, she managed to look down her nose at me. "I know them's mine. What kind o' coblyn would I be, if I couldn't recognise mine own kin?"

I didn't doubt her.

It felt like too much of a brash coincidence, the bluecaps turning up right in front of our noses. And how did the quiet-eyed thief fit in? Did Mercer hire her? Or maybe she simply sold him the bluecaps. Either way, he'd be making all that money which should be rightfully mine.

But that wasn't the worst of it. Suddenly, I found myself robbed of my thunder. My one bluecap was nice, but not as nice as five. And all anyone would remember was that Edric Mercer had them first. He's always first. Bastard.

Gloom enveloped me as we both walked reluctantly back to my pitch. So much for waves. So much for glory and a fantastic tale to tell. So much for my chance in the spotlight.

Sod this Market. Maybe I'd just pack up and leave so I didn't have to see Mercer's smug face again.

I looked up, trying to shrug off the descending melancholy.

And then, across the crowd, I saw patient, quiet eyes.