"We've been at this for an hour, Ang. Are you sure this is working?"

"Caudy geg."

"What does that mean? It's no use talking Welsh at me."

"Shut up."

I observed her for another minute, watching her brows knit closer and closer together while her mouth and eyes screwed up into tight wrinkles in her face. You'd think her features were being sucked inwards by the force of the world's most bitter lemon.

We'd retreated to this deserted car park to start our search for the missing bluecaps. So far I had been allowed to sit on the tarmac and say and do bugger all.

"Ang–"

"Oh,cach. I give up." She flung her cap on the floor and stamped one heavily booted foot as she rose from her seated position. As far as I could tell (seeing as she wasn't talking to me at the moment, what with having allowed her bluecaps to be stolen, and all) she had been staring intently into the blue flame of her old miner's lantern. She'd done more than just stare, actually. She had started with staring and after a while began tapping carefully on the the glass, which progressed to an insistent knocking, then a frustrated rapping; finally she'd shaken the lantern about and shouted at it in Welsh. Clearly, none of this had had the desired effect.

She gave the lantern a half-hearted kick and stuffed her hands in her pockets. "Dunno what's wrong. They just ain't talkin' t'one another," she muttered.

"What aren't? The bluecaps?"

"Aye."

"Are they connected to the one in the lantern?"

She flashed me a condescending glare. "O'course. Wha'did I tell you them bluecaps were? Mine own kin, souls o' coblynau past." She tapped her lantern. "This were me mother, once. This spirit should be able to feel where all its kin are, same as it can feel the whereabouts of a good vein o'coal."

"So what's the problem?"

"Dunno. It just doesn't seem to know where t'go." She scowled, kicking at the dirt. The anger washed out of her face and was replaced by gloom. "S'your fault," she mumbled, dejectedly.

I frowned. It wouldn't be so bad if it was only a tin of baubles I'd lost. Trinkets go missing all the time; you can't get attached to things in this business. But no, this was a box of Ang's ancestors that had been stolen away. Not to mention an incredibly valuable investment. Those bluecaps would sell for hundreds. No, maybe thousands!

It made me feel rather gloomy myself, thinking of that sales opportunity sitting on a pretty shelf in some oblivious girl's home. I bet she had no idea what she'd made off with.

Well, we'll see about that.

"C'mon Ang, it's not over yet. I've got methods too, you know."

She regarded me doubtfully. "Like what, merchant man? You a thief-tracker too, now?"

Ignoring her, I opened the boot of my car and rummaged inside until I'd made enough space to open the secret compartment. You know, that compartment you're meant to store your first aid kit and emergency tools in. Mine contains different sorts of tools.

"Grab the road map out from under the seat, would you?"

"Do it yeself."

"Spread it out on the bonnet, please."

"Oh, I'll do what I'm tole, shall I? Ceri grafu."

"And don't swear at me, please."

"Cont."

"I'll pretend I didn't hear that."

I emerged with the small quartz crystal and silver chain I had been searching for. Ang was already waiting by the front of the car, scowl still in place. It turned to a sneer when she spied the crystal dangling from its chain.

"Scryin'?" she said. "I ain't using that witchery. Them heathen crystals ain't right."

"You've got a weird idea of what's heathen. You keep the soul of your dead mother in a lantern, for crying out loud."

"S'different. Things in the ground be pure. Shouldn't be taken out and tinkered with."

"You used to be a miner!" I exclaimed, aghast. "Your entire job was taking things out of the ground so that they could be tinkered with!"

She shrugged, suddenly uncomfortable. "S'different. Coal n' iron is safe. But crystals... They got them vibrations, you know?"

I did know, sort of. Some crystals and other rocks are really good at resonating with the things around them, and they can be sort of, tuned to mimic certain vibrations. And if you think of these vibrations as types of energy, well, it means you can do all sorts of things with it. Take the crystal in my hand, for example. When it came out the ground, it was just a lump of quartz. But after several weeks of fine tuning in a crystal smith's workshop, it can now mimic the resonances of any item or person – and with a bit of practice you can use it to find those things on a map.

You have to let the crystal 'tune in' to the correct vibrations first, though. To find a missing person, you need something like a scrap of their clothing or some of their hair – anything of theirs that might still hold those residual vibrations. To find the missing bluecaps, I knew just the thing we'd need.

"Ang, is there any chance you can get that bluecap out of your lantern?"

"What for?"

"Do you think it could, sort of, sit on top of the crystal? It needs to know what it's looking for, you see."

"No, gwas.I ain't letting it near that thing."

"C'mon, Ang. Do you want to find the others? This might be our only chance to find them before they're out of reach."

I could see worry and reluctance battling it out over her features. She'd retrieved her flat-cap and was wringing it through her hands.

"I promise it'll be fine, Ang," I said, soothingly.

"Your promises ain't worth much, gwas."

"That's unfair. I don't lie. Often."

"Yet somehow ye still manage to steer well clear o' the truth."

"We all have our flaws."

"Hah!"

She chewed it over, tapping her foot and wringing her cap. I glanced pointedly at sky, where the sun was well on its downwards arc to meet the horizon. Ang exhaled noisily and fetched her lantern.

"Don't make me regret this, gwas."

"Stop worrying. Can you get it to hang onto the crystal, somehow?"

She unscrewed the lantern's cap and held out her arm. The bluecap flame noiselessly drifted upwards and wrapped itself around her wrist. It was an eerie sight. The blue flame flickered around her skinny fingers as she reached towards the crystal. It slid off, folded itself around the sparkling quartz and hung there, dancing and shimmering in the breeze.

I turned to the map spread on the bonnet, the silver chain clutched tightly in my fist. Ang had sensibly pulled out the localised map of Cumbria. The town of Cockermouth lay just to the west of the Lake District and sat upon the River Derwent and River Cocker (this place is a giggle-a-day for me). I held the crystal over the centre of Cockermouth and tried to focus. Or rather, unfocus. The less there you are, the better – means you're not providing as many distracting vibrations, or something.

"You sure you know what you're doin'?" said Ang, eyeing the crystal suspiciously.

"I'm not an expert, no. But I know the basics. So just be quiet and let the crystal do its thing, all right?"

She folded her arms grumpily, but kept quiet. As I relaxed, the crystal began to stir.

It was the gentlest of movements at first, barely a back and forth. But the movement grew into a slow, swinging circle above the town. Our eyes followed it keenly as the circle grew broader, faster. Faster still, and wilder. The chain wrenched on my grip and the circular motion dissolved into a frenzied whizzing to all corners of the map. A biting pain shot through my hand and up my arm. I yelped, yanking my arm away and dropping the crystal onto the tarmac.

Ang darted forward and scooped up the fallen bluecap, which shrank into her embrace like a frightened child. She glared angrily at me. "Look what you did! Did you know it was going to do that?"

"No," I said, sucking my fingers. They ached.

"I tole you it wasn't right messin' with them tinkered crystals. Got us nowhere, eh?"

"I wouldn't say that." I picked myself up and gingerly plucked the crystal from the ground. It felt hot. "We now know that the woman who stole those bluecaps knows what she's doing," I said, darkly.

"What's that supposed to mean?"

"It means that she probably has some kind of spell or talisman hiding them from prying eyes. Something that muffles the signal. She knows exactly what she stole. Probably knows what they're worth, too."

I could see the panic in Ang's eyes as this sank in. "How we going to find them now, gwas?"

"I don't know," I admitted. I'd used up my ace and now I was back to square one. I didn't really want to say it, but our chances of ever finding the bluecaps had become extremely slim, because the wards hiding them were powerful. The signal hadn't just been muffled, it had been completely drowned out by something so loud it hurt – the crystal had been desperate to be anywhere but over the map.

So this woman, this thief, could be anything. Witch, maybe. Perhaps not even human: plenty of strange beasties have picked up the knack of walking around in human skin.

In Ang's arms, the bluecap suddenly glowed brighter.

"What's it doing?" I asked.

"Dunno," said Ang, equally puzzled.

The flame leapt from her arms and floated in the air for a moment. And then, with a quiet pop, it shot off into the distance.

"Follow it!" screamed Ang.

I was already running. Around a corner and down an alleyway, then out into a wide street where perplexed shoppers became angry shoppers as I crashed through their midst. The blue glimmer weaved in and out of sight ahead of me. The second wave of startled cries from people behind told me that Ang was hot on my heels.

We turned into an emptier road, and then I was hopping over a fence – oh, that must be Cockermouth Castle up ahead – we barrelled past the ruins and into the trees following the line of the castle walls. The trees ended abruptly, and so did the ground.

I caught myself on a low branch and flung out an arm to catch Ang as she flew past. We clung to the tree and fought to regain our footing. We were inches away from slipping down the muddy bank into the swirling waters of the Derwent.

"Where's... where's th'... bluecap?" Ang spluttered, in between heavy gasps for breath.

I pointed. It was hovering about a metre above the river, where a pile of rubbish was floating on the surface.

"You don't think she chucked 'em in the river, do ye?" said Ang, horrified.

"I highly doubt it." I peered closer at the mass underneath the bluecap. "Look at that rubbish in the water. It's not moving."

"So?"

"See the eddies around it? There's something solid under there, anchoring it in place."

Ang looked at me anxiously. "We're not gunna have t'swim are we, gwas?"

I cast around for a large rock and found one to my liking. I hefted it in one arm. "I hope not."

The rock curved in a nice arc and dropped down right on top of the floating rubbish heap. I wasn't sure what I was expecting, but the pile didn't sink. Instead, it rose.

"Gwas," whispered Ang fearfully. "What is that?"

I've never encountered a rubbish monster before, and by all accounts that's exactly what this thing was. A sentient pile of rubbish. It turned, appeared to spot us, and was now swimming – or wading? – in our direction. We remained frozen, clinging to our tree as the creature reared in front of us.

From within the depths of weeds and trash a deep, slow voice emanated:

"Did you throw that rock?" it asked.

"Uh, yes. I did," I replied.

"Why did you do that?"

"I was trying to see what you were. Sorry about that."

"What are ye, y'big pile o' ysbwriel?" said Ang from her branch.

The thing seemed to sag, and sadness filled its voice.

"You would know what I am if I had my coat. They call me Shellycoat, for my beautiful coat of shells." It let out a sigh that sounded like waves.

"Looks like a pile o' rubbish to me," said Ang. I shot her a chiding look but she paid no mind. "Where's your shells now, Smellycoat?"

The shellycoat sagged further, so that it was only just above the water it sat in. The mass of trash rattled as it moved: tin cans, plastic bottles and sweet wrappers glinted in the dying sun.

"Stolen," it said, mournfully. "By a lady with quiet eyes."

Easy connection to make there. Spot on about the eyes. Her gaze had been so... patient.

"Funny you should say that. We've also had something precious stolen by a lady today," I said. "Perhaps you've seen it?"

"Many things float down the river. What does it look like?"

Ang opened her mouth: "It's a–"

"Bit hard to describe, really," I butted in. "Maybe you could show us the things you've found today? Could be a bit of a reward in it."

The shellycoat sighed despondently. Then it seemed to shrug – a ponderous, undulating movement – and a few choice objects rose to the surface of its matted coat. Among them were an ornate bollock dagger, a very intricate (if damp) Japanese omamori amulet, and, best of all, a plastic bottle containing one glowing bluecap. I had to grab Ang by the wrist to stop her diving straight for it.

I pretended to inspect the array of items. I rubbed my chin thoughtfully and said: "You know, this is a very exclusive mix of things. I have trouble believing that they all just washed downriver."

The shellycoat sighed again. "I met the lady once more today. Moments ago. I asked for my coat back, but she refused. I dragged her into the water, but she stung me. These things fell from her bag before she got away."

A picture was starting to form of this woman, of her life. I bet all of these items were stolen from someone else. I bet it's how she makes her living. She's a professional.

"Say, what's the blue thing in the bottle?" I asked.

"It's a pretty light. It floats in the air and the water, but I put it in a bottle so it won't get away. It lights everything up nice underwater."

"That's pretty clever."

"Yes."

"Thing is, it looks to me just like one them bluecap things. You ever heard of them?"

The shellycoat swayed in a way that I took to be a shake of the head.

"Well, they're ground-dwelling spirits, see. Very unlucky to have in the water; they'll drag you down into the depths of the earth if you let them."

"Into the earth?"

"Yep, where it's cold and dark–"

"I like cold and dark."

Ang nudged me. "Mines are bloody warm, y'know."

"Warm, I mean," I continued, back-peddling. "Humid. And oppressive, all those tons of earth weighing down on you. Not like the cool, free-flowing waters of a river." I shrugged. "Just saying. It pays to be careful around these things."

"I like the light," said the shellycoat, doubtfully.

"Yes, but one day that light may lead you into places you wish you'd never gone." Now there's a piece of truth if ever there was one. "Anyway, I'm not interested in the bluecap. I don't want that kind of misfortune for myself, no sir. I might be interested in taking the other bits off your hands, for a price, of course."

"A good price?"

"A fair price. Quite a bit of water damage, from what I can see. That dagger's going rusty – you can see it's obscuring the fine detail there – and that soggy amulet is only made of fabric and paper – the colours are starting to run, see; at worst it might be unreadable!"

The shellycoat shifted, or rather, undulated in thought. It wondered aloud: "Is it enough to buy a new coat?"

"A coat?" I repeated. "Made of shells, you mean?"

A few shiny foil wrappers peeled away in the breeze as the mass nodded.

"This is a poor substitute. I miss the rattle of shells, not the clanking and rustling of this... this..."

"Rubbish," said Ang, flatly.

"Well, Shelly – may I call you Shelly? – I'm afraid I don't have a coat of shells to sell you. I do have some interesting charms and potions though, but, oh dear, I've left them all behind. It's a long way back, and I really can't stick around. Is there perhaps a favour I could do for you as payment?"

"A favour?" said Shelly in a slow, bewildered manner.

"It's the traditional on-the-spot payment for these sorts of things. I don't suppose you have any thorns you need pulling out of your paws? If you even have paws. Maybe a nasty bit of fisherman's netting we could remove for you?"

"No."

"Dang. And I rather fancied that dagger, too." I tapped my lips, eyes raised to the sky, then snapped my fingers. I suspect it made the shellycoat jump. "Here's an idea, we could get rid of that bluecap for you. It's not a risk I'd like to take, having that thing about my person. But seeing as there are no other alternatives, I'm happy to offer it as payment. What do you think?"

"For all of these things?"

"I would settle for just the dagger."

"No."

Ang let out an exasperated sigh next to me. "Can't we just–"

"In a minute, Ang," I said, placing a soothing hand on her shoulder. I turned back to the shellycoat. "What do you think my offer is worth?"

It spread itself wider and bobbed up and down in the water. For a moment I worried it was going to sink and take the bluecap with it. Then it said: "The paper charm. You may have that."

"What!" I exclaimed. "That's daylight robbery, that is! I offer you this good service – which most people would be loathe to undertake, mind you – and all you want to offer me is a bit of soggy paper!"

The bobbing became more agitated. "Won't sell the dagger. You think it is valuable. I will trade it with someone who can give me a new coat." The dagger sank back into the mess of weeds and rubbish. "But I offer you one further item. Your choice."

I cast my eyes over the trinkets remaining. Largely worthless, but I selected a ring, anyway.

"This will do," I said, begrudgingly. "This ring and that charm, so that I may dispose of your bluecap problem."

"We are agreed."

Wiry green tendrils, which I had assumed were just weeds, now grasped the amulet and bluecap bottle and held them out to me. They felt somewhat slimy in my hands.

"Pleasure doing business with you," I said, as the shellycoat disappeared beneath the water. The surface bubbled for a moment, and that was the last we saw of it.

Ang put the rescued bluecap away safely in her pocket. The other zipped along behind us as we walked back to the car.

"That was mean, you know," she said, after a while.

"What was?"

"The way you tricked that ol' Smellycoat. Bluecaps ain't no burden o' bad luck."

"They do lead you underground, though."

"Not in the way that you meant, gwas."

"Doesn't matter what I meant. Didn't lie, did I?"

"Didn't tell the truth, neither."

She ducked behind me as a couple passed us in the street. It's easy for such a small creature to go unseen. Half the time people don't see her simply because they don't look down. She continued wandering behind me until we reached the car, all the while a distracted look of deep disquiet on her face.

I gave her a friendly pat. "Don't worry about Shelly, I'm sure it'll be fine. As for us, we're more than fine, we just recouped our losses today!"

"We only found one bluecap," she said, icily.

"Yes, and we also found this incredibly valuable omamori amulet! They're ten-a-penny at Shinto shrines, like your basic good luck charm. But this one is far more complex, a really strong protection ward, I think. Probably old, too. A lot of money in that."

"I thought you wanted the dagger?"

"So did Shelly," I said, smugly. "Just an ornamental knife, nothing special. We got the real prizes today."

"You think that pile o' rubbish will find a new coat?"

I shrugged, and started to re-arrange my wares in the boot. Probably best to move on from here. "Surely all it's got to do is collect some more shells. Plenty of them about."

"Plenty o' bluecaps, too. But only a few of 'em are mine."

I stopped and turned to look her square in the eye. I thought about crouching down to her level, but knew she'd consider it to be the condescending gesture it was. "Look, Ang. No one is more sorry than me about your bluecaps. That's a tidy of sum of profits I'll never see again; I wish I hadn't let them out of my sight. The fact that we recovered one bluecap today was just a piece of good luck. I'll be honest – I don't hold any hope of finding the rest."

"What happened to 'I'll find a way'?" she said, accusingly. I winced.

"That was before I knew what we were dealing with. This woman clearly has some power behind her. You saw the size of that shellycoat: she wrestled with it and won? She's stolen all these different things and has the ability to keep them hidden? I don't know what kind of aces she has up her sleeve, and I don't want to be the idiot who finds out the hard way. Not to mention the fact that she's probably skipped town already – I would, if I'd just had a brush with a dissatisfied customer."

Ang's eyes narrowed. "Ye a coward, gwas?"

"I'malive, Ang. And I intend to stay that way."

She turned quiet, but it was that loud kind of quiet that lets you know a sulk is brewing. I awkwardly tried to pat her shoulder. "C'mon, Ang. Let's get something to eat. I'm famished."

She nodded sullenly. Looks like I was going to receive the silent treatment again. I didn't much mind, it would be nice to have some peace and quiet even though I was going to find it hard to enjoy properly.

Ang might think me a coward, but I had good reason to be cautious. Spend any amount of time in my world and you quickly learn there are some very big fish sharing the water with you. I'm not exactly one to preach about looking before you leap – heaven knows I've jumped headlong into my share of dangerous situations – but even I know to back off when the fall looks too high. And to me, something about this theft smacked of a very, very long drop.

And normally this would be the end of it. I'd cut my losses and move on. But something kept dragging my thoughts back to the enigmatic bluecap thief.

You see, I had this awful, troubling notion bubbling away in the back of my mind. Somehow I knew that this wasn't the last we'd seen of the woman with the quiet eyes.