When night comes it settles everywhere in the city except Stone Circle.

That's part of the Pact, Silly Olwyn told me once, but it's her job to tell lies and I have made a practice of ignoring her.

My name is Lantern and I sell days.

While the rest of the city sleeps, Stone Circle comes alive; and it is never more alive than on the night of the Fall of Changes.

Which, as it happens, is tonight.

How lucky you are.

Triste de la Monde and I are lying all tangled together on a black leather sofa inside the House of Games, waiting for the sun to set on everyone but us so the festival can begin. Triste makes a thoughtful noise. "Well, Lantern," he says, "there appears to be a fruit in your ear." He waves one hand and is suddenly holding a glossy red apple. "See that?" he says smugly. "That's magic."

"So impressive."

He grins and says with his mouth full of apple, "I know."

Nobody knows about Triste de la Monde. Even I am not quite sure. The only mask he wears is Harlequin, purple and green and glittering, eyes slanted upwards and mouth twisted in a sarcastic smile. If you make your way down to the dark part of Grassmarket—the part that is ours, the part that belongs to the Circle—you will see him leaning against the wall. He might seem very nonchalant, but make no mistake: if he does not approve of you, you will never find your way to Stone Circle no matter how hard you look.

Oh-Laliro once made a joke about how I had seen inside that Harlequin mask and he inside mine. I laughed, of course, and then I locked her inside a rainy Monday for two weeks.

Just thought I'd let you know.

"Look," Triste says, and points. Out on the street corner an orchestra of ragged bare-faced boys playing maple-wood mandolins tunelessly tune up; they belong to Mister Knife, and their eyes are just a bit too feline.

(If you ever find your way to Stone Circle it would probably be a good idea to stay away from them.)

Triste and I know that this is the signal. The night is about to begin. We untangle ourselves, fasten masks tightly, and go out to take our places in the street. From dusk to midnight is the time for conducting business, whatever kind of business that might be. From midnight to dawn is time for the Fall of Changes.

The street performers stretch and sharpen their knives. Old women in beak-nosed masks lay blankets on the cobblestones and set out charms in neat rows. (These spells are nothing more than ribbons and pinches of herbs; if you want the real thing, you come to me.) Triste and I stand for a moment beside the middle monument, tasting air.

I say, "It smells like magic already."

"It smells like winter."

Winter is Stone Circle's season, because it is a season of night. In winter we arm ourselves with scarves and long coats and flasks full of hot chocolate that's really mostly brandy, and the Circle is not quiet from six in the evening until six the following day.

I take my place in the street, inside an alcove guarded by a grinning gargoyle, only a little distance away from Silly Olwyn's stall. The bell rings, and with everyone else I tip my head upwards to the sky.

The sun sinks and sinks and disappears.

Now Stone Circle is awake.

Now there are fire-breathers, jugglers, musicians; there are women all in white who reach into mirrors and pull out black flowers dripping red, and small men dressed like miniature soldiers dancing awkwardly at the end of ropes, while bears in top hats crank out music and crack whips. Visitors spill out in the midst of our people. They come in two kinds: the ones with huge eyes, either terrified or delighted and trying to take in everything, or the ones who do not look anywhere at all but cut through crowds with their heads held high, intent on their purpose and very self-assured.

It is usually the second kind who are my customers.

Of course, I get the normal ones too. I'm sure you can guess the stories. Wives of dead husbands wanting one last chance to say "I love you." Men who have cheated on their girlfriends and wish they hadn't. That kind of thing.

But then there are the other ones.

Tall men all in black, or women wearing Victorian dresses, and the air they bring with them is laced with prickles of magic. These people do not smile. I give them what they need and they leave; if you were to follow them through the streets afterwards, there is a strong chance you would find yourself in a back alley of the real city with no idea how you got there.

Are you afraid yet?

Once the King of England came to see me. Not the King of this England, of course, but a King of England just the same. He was very majestic. He said, "Are you Lantern?" and I said yes. He said, "Can you change history?" I told him no and apologised. "Oh," he said, and that was the end of that.

Silly Olwyn ducks her head around my alcove and pokes a cup of tea at me. "Have you felt it?" she demands.

"Felt what?"

"Pay attention, Lantern. There's something wrong with the city."

I swallow a mouthful of tea and grimace. "What do you mean?"

Silly Olwyn hunches so close that the long nose of her mask pokes me. "It's creeping in," she whispers.

Which is, of course, impossible. We have our Pact. We keep away from the city, and the city keeps away from us, so our place would still be ours even if the rest of the city got blown up—it would just be a little bit harder to get in and out. Those who signed the Pact know that if they ever broke it they would find things among their buildings and tangled streets that they have not seen even in their worst nightmares.

So I say to Silly Olwyn, "Don't be silly."

But even now I can feel something. It is black-flavoured, all charred and cold, the taste of dead burning.

Silly Olwyn clucks and mutters. "Lantern," she says sharply. "Pay attention. You have a customer," and she disappears.

He stands at the opening of my alcove. He is thin, very angular, very haughty; his black leather jacket fits him neatly as a coffin. He smokes a hand-rolled cigarette and does not have to speak for me to know that he is older than he looks. "You're Lantern?" he asks doubtfully.

I say I am.

"You're the one who sells days."

"Yes," I say. "My speciality is Saturdays but I can do just about anything."

"Just about." He grinds his cigarette out on my gargoyle and examines me. "Nice mask."

I say thanks.

"Do you know who I am?"

"Yes," I answer, "you're the Devil."

At this he seems ever so slightly put out. "Well. Yeah." He crosses his arms over his chest and sighs. "You can call me Tom Brimstone."

"You can call me Lantern."

"Believe me, I was under no compulsion not to," he says, beginning to look annoyed.

Beyond us the second bell rings, marking halfway to midnight.

I say as politely as I can, "Is there something I can get you?"

"Yeah." He fishes tobacco and rolling paper from a hidden pocket. "I need somewhere to stay for a while, somewhere I won't be found. You sell days, right?"

I nod slowly. Stone Circle buzzes with noise and nighttime, and outside of our pocket of magic I can feel blackness, burning. I say, "You want a day that's not in the week."

Shadows make his whole face black. "I can pay you very well."

"I know."

The darkness outside Stone Circle gets darker. Very, very few people have asked me for anything like this, and most of the time if someone does I will laugh in his face; but this doesn't really seem like the time to laugh. The Devil, Tom Brimstone, stands and watches me as I think, dangling a skinny cigarette and spilling smoke from his nostrils.

Finally I shake my head. "No," I say. "I can't do it. I would need magic, much more than I have now, and supplies I can't get. If I tried tonight I might as well stab myself and get it over with."

He drops his cigarette on the ground. It lands in a puddle and hisses. "Well."

"I'm sorry."

Tom Brimstone shrugs. "I might as well stay in the Circle for the night. Why miss the festival just because the world is going to end, right? If you change your mind I'll be around."

I'm still standing there for a long time after he is gone, biting my nails, squinting my eyes at the cobblestones.

The third bell rings. I make my way over to the middle monument with the rest of Stone Circle. The Four Sisters appear on top of the monument, dressed all in red, wearing plain white masks that do not smile. The Four Sisters—History, Malady, Alchemy and Threnody—are the four guardians of this place, and they have been here since time had a name. They say the words that start the festival; and then the streets go wild. Men in dragon costumes jump from the high buildings and swoop among us, roaring. Fire crackles in the sky. Mister Knife's women slink through the crowds, and when the city's moonlight hits them it almost seems as if they are not women at all, but long and velvety cats. Music comes from everywhere. People dance in pairs, or trios, or big drunken groups that tend to bump into other drunken groups and sprawl all over the road.

I find Triste watching one of the street acts. I drag him down a deserted alley, and shove away our masks and kiss him until neither of us is cold.

Then we go back to the festival.

No one in the Circle is certain exactly what the Fall of Changes celebrates, but we still celebrate it as hard as we can. Most years, by the night after it is nothing but a blur of light and colour in memory. There is a spell some of the old ones do which makes any drink in the whole Circle turn to very strong alcohol; by the time the spell is done, most people are already so drunk that they don't even notice.

I watch the street performers breathe fire from their oboes, and I dance clumsily with Triste through the streets, and I cheer along with everyone else when Everesque kisses Malady on top of the middle monument. When the crowds drift off to watch Mister Knife's shows in the House of Games, Triste pulls me aside. "Lantern," he says. "What is it?"

"What is what?"

"Don't be irritating."

"I am having a wonderful time. You know this is my favourite night of the year," I say, and all I can think about is magic, a new day, just how I would go about making it.

Triste sighs dramatically. "I am not an idiot," he announces. "And I think I know you well enough to know when your mind is somewhere else entirely." I can tell his eyes are frowning behind the Harlequin mask.

I give up. "Have you ever heard of Tom Brimstone?"

"Tom is such a common name."

"He's the Devil."

"Ah," Triste says, "that Tom Brimstone."

"He came to me tonight."

"As a vision?"

I roll my eyes. "As a customer."

Triste stands very still. For a moment I am glad that he is still masked, even though we are alone, because I do not think I would like his expression. "Go on," Triste murmurs.

I tell him all about it, and what Silly Olwyn said, and what I felt outside Stone Circle.

"Lantern," Triste says, sounding dangerous. "Lantern, I want you to stop and think for one second."

Yes. Think. I think about magic, about words full of power, walls of air, new things that no one has ever written down; and the taste of it in my mouth, the sparkle threading its way through my bones, and I think about the challenge.

"Not like that!" He throws up his hands to the city's dark sky. "Lantern—"

"I want you to come with me."

Triste crosses his arms, suddenly all disdain, all haughty Harlequin in his top hat and black coattails. He does this occasionally. I like to see it as his version of a temper tantrum. He angles his head to one side, and I know that is it both deliberate and carefully calculated so that the torchlight will catch the glitter on his mask and make it blaze. I think Triste has had a lot of time to think about these things.

I say, "On the other hand, I could just go alone."

We find the Devil inside the House of Games, sitting alone on a high-backed red velvet chair that I'm willing to bet the House didn't know it had. He raises his eyebrows and blows smoke at us.

"I'm going to need something of yours," I tell him, "something I can use, and I'm going to need somewhere quiet, and I'm going to need three times the pay."

Tom Brimstone unwinds himself like a snake. "Done."

Stone Circle is shaped like a snail, or a seashell, or a Danish pastry. There are streets wrapped around lines of buildings wrapped around more streets, all the way in to the centre, which has the middle monument, and where most things happen. If you come to the Circle you will want to walk those streets forever. Where else would you see the penny-witches and tightrope walkers and magicians and performing goldfish?

Well. Trust me. If you ever do come to the Circle, do not make the mistake of staying only to the streets. Walk down a swirl of cobblestone and house, and find your way into one of the shops. It doesn't matter which one. Doctor Mirror's shop, or Sigh's, Tage's, Casiel's, Petard's. Any of them. Trust me on this.

Triste flicks one dismissive hand at the door to Malidar's workshop and it flinches away from him. "Will this do?" he asks me, in a way that makes me not quite anxious to be alone with him again.

"Where's Malidar?"

"Somewhere else. I'll make sure it stays that way."

Malidar is a woodworker. He likes to make animals. There are a few of them still scattered around the store: antelopes and horses two hands high wandering over the floor, grazing on sawdust; birds perched on the curtain rails that shuffle their feathers with neat wooden clicks. Two mahogany cats lie curled up on the counter, watching us.

"Maybe," I say to Tom Brimstone, "you should put out your cigarette."

He hisses something under his breath.

I find blankets in a cupboard and pile them in a nest on the floor of Malidar's workshop. A wooden antelope clops over and snuffles my hand for a moment before losing interest. Tom Brimstone hands me his silver lighter. I turn it over and over, feeling the warmth from his hands and the magic buried deep down.

Outside, Triste spits out a string of curses that ends with my name. I grin behind my mask.

You cannot come to Stone Circle without seeing a big magic. It will happen at some point, whether it's part of a ritual or just pure chaos. You will feel the air of this place get clearer, colder, the stones beneath your feet harder, everything brighter. Magic makes this place more real. It also hurts like hell the next day and can wind up killing you. But who are we to care in the face of ritual and chaos?

I settle myself into the nest of blankets, with one hand on Tom Brimstone's lighter and one on the floor, and concentrate on the magic sparking through my blood.

I work and work until the whole world sways. Colour drips down the walls of my vision and voice melts into voice. I work until my hands shake, and then I keep working. Magic is a contradiction of itself: it is like being rooted to the earth, the old earth full of power, and it is like flying away from your own body. Those two feelings, both at once.

From somewhere very far away I can hear Triste saying, "Come back, Lantern. That's enough."

I have a body again, which aches, and then the world has shape. I remember that I need to breathe and take a cold swallow of air.

Triste moves away from me. I wonder what exactly I was supposed to be doing, and then I remember, and wonder if I did it.

There is something hot and sharp tucked into my fist. I examine it: a small silver key, already cooling, sharp as a vicious grin. It is perfect. It tastes of thunderstorms and strong magic. I almost don't want to let it go.

I give Tom Brimstone the key to his new day on a silver chain, which he hangs carefully around his neck and asks, "What do I owe you?"

"An explanation," I say, and then hope he won't open up a portal to hell as punishment for my audacity.

He just nods. "I thought you'd want one. Okay. Things are changing in the real world. You know that, don't you? Someone did a stupid thing and now I have to find some way to undo it. If I were you, I'd tell all my friends to stay out of the real world for a while, if they don't want to see some really nasty stuff."

I smile underneath my mask. "Some of the city people might say we're fairly nasty."

"Clearly," he says in a voice dripping disdain, "the people in the city don't know a goddamned thing."

I hear something from Triste that might be a quiet laugh.

He shrugs. "I'll be back. I'm going to need some help. If I'm not back, well—you'll probably know what's happened by the rivers of blood, and the fact that you'll all be dead."

I chew on my lip.

Tom Brimstone grips the key on its chain. "Thanks, Lantern."

"Okay."

"See you in a few," he says, and disappears in a coil of smoke.

When I wake the next day I hurt all over and Triste is gone. I fumble on a new mask and tiptoe through the silence.

This is how Stone Circle is in the daytime: everyone rests. The streets whisper emptily to one another. At the quietest time you could stand on the middle monument and breathe one word, and the word would echo down the spiral of roads and houses until it came back to you as a shout.

Of course, that would be quite stupid. Something would probably get annoyed. You might find yourself scuttling through the gutters in the shape of a rat, and you might not; there's really no way to tell.

I find Triste lounging against the wall in Grassmarket Street of the real city. He tips his hat at me and says nothing.

I say, as if I don't care at all, "He said he needed help."

"He did."

"Do you think he'll find it?"

"I think he knows where to look. He is the Devil."

"Do you think he'll be back?"

"Why don't you just say it?" Triste says. "You want to follow him. You're curious, and you want to follow him."

"I can't," I say sadly. "I built the day so no one could get in if they don't have a key."

The traffic hums its way past. City noises spit at us across the gold-stoned buildings and black churches.

"Ah," Triste murmurs.

I glance down and see his hand open. A tiny key glitters on his palm.

Triste pulls me closer, and I know that under Harlequin's face his grin is wicked. "I guess it's a good thing I made a copy."

I take his hand, and fit the key into the lock of the city, and turn it hard.

A door swings open somewhere else.

Triste and I step inside.

If you want to come and see me, this is what you do: walk down the dark part of Grassmarket Street just before sunset, and look for Triste, who you will know by his mask and his top hat. If he is standing there, then you'll know that we managed to help the Devil.

If he isn't, well, you're probably dead already.

Tell Triste that you're looking for Lantern. If he likes the look of you he will send you down. Close your eyes for this part. Once you are in Stone Circle, you will find me underneath the gargoyle, beside Silly Olwyn's stall, straight to the right of the middle monument. I promise I will be glad to see you.

But only come if you know what you want, because Stone Circle has no patience with people who waste its time.

My speciality is Saturdays but I can do just about anything.