I stood in the alley behind the club, my back against the wall, inhaling deep gasping breaths and desperate to expel the aftershave and baby powder that I was sure was clogging up my lungs.

Oscar had that effect on people. Stay in his company too long and you couldn't breathe. I'd seen it on the faces of others, that strangled look of panic you only get when you know a predator is near, but I'd never experienced it before, not like this.

The air in the alley wasn't that much better than inside Oscar's office, thick with the cloying stench of piss and damp, where the rainwater had infected the base of the walls, but even this tasted better than inside. Close by, water was gurgling out of a broken moss-covered drainpipe, the grate below filled with sodden cigarette packets, remnants of club flyers and cig butts, forcing the water to overflow and stream across the alley towards where I stood. The water reached my feet and I numbly watched as it seeped into the open-toe front of my heeled shoes and I willed it to rise, to become a stream, a river, flood the whole damn alley and carry me under.

In my hand, the bag felt like a leaden weight, tying me down to this place, to Davey, to Oscar. But even then, even after everything Oscar had said and more importantly, not said, I thought take something, reach in and take something, swallow it down and everything will be okay, everything will be alright again. Exhaling, I leant my head back and it was then I spotted it. A security camera fixed right on the entrance where I was standing.

That's right, take a good look, you dirty bastard.

I couldn't stay there, I had to keep moving. Addi would be waiting for me at the pick-up point, although for the first time in ages, I wondered what it would be like to just keep walking and never go back.

With a resigned, sinking feeling in the pit of my stomach and wishing I could flip the bird at the camera, I hooked my arm through the bag handles and began to head down the alley towards the street, hearing nothing but the gurgle of the water as it faded behind me and the clicking of my heels on the uneven ground.

I hadn't gone far when I heard the footsteps.

They were faint at first, so faint that I thought it was just my own, echoing along the alleyway, then growing in volume, in urgency, and I had to look. Just had to. Whether it was that morbid curiosity or something else, something that ran darker, deeper, like a sixth sense you never knew you had until that moment, that awful moment when you know - you feel - that something is wrong. And I did feel it. Like the prickle of goose-bumps. Like the whisper of something cold along the back of my neck that made my hair rise. Like the ominous ticking of a counter down to zero.

And this was it, this was my zero and I had to turn. I had to look back.

I remembered then.

That face from New Year's Eve. That terrible, heart-stopping face that had sent me flailing to the ground. All of them, watching me, seeing me like I was seeing them.

How could I have forgotten?

The face was here now, or at least, one like it, because this one belonged to a different man, tall, lithe, a navy coat unzipped to reveal a white tee underneath. On his head, he wore a black baseball cap. Everything about him screamed normal. He could easily have been one of Davey's crew, except for that face and as he came towards me, he grinned and the scarred skin, molten into deep-set valleys, stretched over his prominent, jutting cheekbones.

Gasping, I stumbled backwards, the damp wall stopping me from falling right onto my arse and I watched in stunned horror as he raised his arm, stretching it out in front of him.

He was going to shoot me. He was going to shoot me and I was going to die right here, in this stinking fucking alley, wearing this slutty dress and I wasn't ready. After everything I'd done to push the limits, after every time I'd danced across the line and dared Death to take me, I wasn't ready. Not now. Not like this. The panic surged, rolling under my skin, forcing the air out of my lungs and crushing my heart in my chest.

With his arm outstretched, the man curled his fingers up, almost in a beckoning gesture and it was then I realised that he didn't have a gun at all. In fact, he wasn't holding anything.

Instead, he made a half-fist as if grabbing at the air and he pulled.

In front of him, the air shimmered, undulating like ripples on water and everything between us began to shift, distort, fold inwards as if he'd split the air in two and it was rushing in on either side, being pulled into an invisible abyss that seemed to stretch from him to where I stood. The walls of the alley were bending impossibly, the ground was rolling, almost as if I was looking at everything from under water and I was drowning in it all, feeling the tide rush into my mouth and nose, choking me.

He pulled again, clenching his fist tight and giving a sharp tug and I felt it as if something was sucking on my skin, pulling on my body. I stared, unable to do anything as my arm, now stretched out as if I was reaching for him, jerked and began to dissolve into the air, flesh tugging from bone, melting, just as the world around me had begun to melt.

The air opened up, like a giant slavering maw, and I watched, stricken, frozen, as half of my arm disappeared into the void - just disappeared. I knew it was there, somewhere. I could feel it. The pain was unbearable. Fire raged under my skin, burying deep into flesh and bone. Gathering in fury, it gripped me, tugging, pulling, as if whatever it was might rip my arm clear of the socket.

I opened my mouth to scream and felt the air suck it away, consuming sound, consuming everything and even as I watched the void swallow up more of my outstretched arm, I thought this is your fault, Casey Brogan, all that shit you shovelled up your nose, all those pills of god-knows-fucking-what and it's finally happened, something in that screwed-up head of yours has finally snapped and all you're going to be left with is this complete fucking madness.

Because this was it. This was madness and chaos and a world turned inside out and upside down, all because I couldn't stop walking the line. All because standing on the edge and just willing myself to jump had been better than everything else in my miserable, pathetic life.

Tears slipped down my face. Everything felt cold and I was struck by that then, struck by how, when my arm felt like it was burning, everything else felt like I'd been plunged into icy, cold water.

I couldn't pull away. I couldn't stop the air from swallowing me up. It was like a bad dream, watching myself disappearing and wishing the whole time that I would just wake up and realise it wasn't real.

Only this was real and it was happening.

My arm had been sucked in right to the elbow now and as the monstrous air pulled it in deeper and I watched more of it disappear, I closed my eyes, too petrified and too stunned to do anything but try and shut it all out.

When I began to be pulled in the other direction, my eyes shot open.

An arm was curled tightly around my waist, a warm body pressed against my back.

'Fucking fight, damn it,' a voice said into my ear, and I looked up and saw another face that had me reeling.

I knew him.

At least, I thought I did. Snapshots flickered through my head as I instinctively sorted through memories, sifting through stored images, but the panic was so overwhelming that I could barely see straight, could barely stand up, let alone think. Where did I know him from?

He reached out with his other arm and I shrieked and turned my head away, terrified that he too was going to twist the air and I was going to be torn apart as my body was grasped from both sides.

A sound cracked in my ears, like the shift in pressure that you get when on a plane, and everything became muted, plunged into an eerie silence that sent goose-bumps ravaging my skin. My arm jerked and I felt the air move, but differently this time, as if its hold on my flesh was weakening. When I looked back, the man clutching my waist had his arm outstretched, but instead of pulling, he looked as if he was pushing back, his palm up, cheek muscles tensed, gritting his teeth with exertion. Minuscule beads of sweat peppered his brow as he pushed outwards and the air in front of me, the air that was seemingly trying to swallow me whole, juddered violently.

Everything seemed to shake as shockwaves rippled back down the alley. A booming shudder rang in my ears and sent nausea rolling through my stomach and up into my throat. Whatever it was seemed to hit the other guy hard and he staggered back, rocked by the force of the wave and the hold on my arm weakened even more.

Without hesitation, the man holding me pushed out again, sending a thunderous wave through the air that felt that it might bring the buildings around us tumbling down, while simultaneously pulling me back. There was a ripping noise and pain - god, so much pain - that for a moment, I thought my arm really had been torn away, but then I was free, my legs collapsing.

Catching me before I fell, he grabbed me by the hand.

'Run,' he said.

Trying to stay upright as I did the proverbial walk of shame out of Oscar's office was one thing, trying to flee from a creature that wanted the air to dissolve me into nothing was another entirely and I struggled to keep up with my mysterious hero as we ran down the alley, back towards the main road. My heels wobbled precariously underneath me and we hadn't gone far when he stopped suddenly, his face twisted with what looked like disgust as he reached down, grabbing each of my ankles in turn and tugging off my shoes. I watched stunned as he threw them to one side.

'You want me to run barefoot?' I could hardly get the words out.

He clutched the back of my neck and pulled my face close to his. 'It's either this,' he said, stabbing his finger in the other direction. 'Or that.'

I turned to look and gasped a strangled cry. The other man - the thing - was on his feet again, his hands grasping at the air, which was rushing towards him and around him in a violent swirl of black; growing and swelling, like some awful, nightmarish maelstrom.

When he tugged at my hand again, I was already moving, trying to ignore the hard, unforgiving ground beneath my feet as it cut into my soles, trying to ignore the scream of my leg muscles as I ran. Behind me, I felt the air move, heard something like the screech of many birds that prickled the hair on the back of my neck but I didn't turn around.

The alley veered to the left and we followed it, our pace never slowing until up ahead I saw the exit onto the main street. Seeing the cars go by and hearing the traffic brought a rush of reality slamming back into me and I remembered why I'd been there in the first place.

Oscar. Davey. The drugs.

Oh, fuck, the drugs.

Even then, with that creature behind us, I felt the pull. The stomach-churning, cataclysmic realisation that I was going to have to explain to Davey - and to Oscar - that I'd lost twenty grands worth of gear. My pace slowed, almost like it had back in the alley and I'd been stuck fast in the moving, shifting tide of air, only this time I was the one forcing the world into slow motion.

The man tugged on my hand, glancing towards me with irritation.

'Come on,' he urged.

'Wait... my bag.' It was pathetic. Reckless. I knew it was even as the words left my mouth. Back there, thundering down the alley behind us was something terrible, something that clearly wanted to hurt me and yet I was still thinking about the bloody bag. About Davey banging Star. Seeing Oscar's hand on my thigh.

'I have it,' the man replied. 'Now just keep fucking running.'

He did have it. I saw it then, the black designer holdall slung over his other shoulder. I hadn't seen him pick it up. I just remembered him grabbing my hand and pulling me away. Saving me.

I gripped his hand tighter and ran, feeling strangely elated as we broke free from the alley and hit the main road.

Weaving in and out of pedestrians, I could see them all, the way they stared as we ran, hammering the pavement, me in my barely-there dress and with nothing on my feet. The streets were alive. Music pumped from shop doorways. People laden with shopping from the January sales milled here and there, cramming what little space there was on the busy street with bag upon bag of bargain-price loot. Everything was loud and crazy and my head whirled as we jostled amongst them, desperately trying to cut a path through the crowds of people.

The man tugged me towards the road and I stared wild-eyed, my heart in my mouth as he pulled me into the oncoming traffic, narrowly dodging cars as we streamed across the road. Horns blasted loudly, brakes screeched, but still he didn't stop.

Reaching the other side, he tore down a side street, never slowing for one second and my feet were burning now, every pounding step like torture. The effects of the coke I'd shoved up my nose before I'd entered the club had worn off ages ago and reality, or whatever the fuck this was, was coming right at me hard and fast and so unrelenting that I was struggling to breathe.

'Please,' I gasped. 'Please, I can't, I need to stop.' I pulled on his arm and slowed, the stitch in my side spiking pain up my body and making me double over.

He yanked on my wrist hard and I yelped. 'We can't stop now,' he said. 'We have to keep going.'

I stared wildly around. 'We're practically on the main road, there's a shit load of witnesses, what can he possibly do?'

Grabbing a handful of my jacket, he pulled me roughly towards him. 'You think you're safe, huh? You think all these people are going to help you?'

He was so close I could feel the warmth of his breath on my skin, could see the tiny scar on his nose and the anger and frustration boiling under a sea of blue in his eyes.

'Being in a crowd big enough to fill Wembley Stadium wouldn't help you now, trust me.'

'Trust you?' I said. 'I don't bloody know you!'

He cocked his head to the side, one brow arched. 'You want to take your chances on your own? Because I can do that. I can leave you here.'

My ears popped, a thunderclap of sound that sent me plunging underwater and I swayed slightly, feeling disoriented and dizzy.

At the end of the side street, the other man stood in the middle of the black storm, with people passing him by like he wasn't there, like they couldn't see what I could see. How could they not see him? Why were they not fleeing?

'What the Hell...' I whispered, terrified.

'Now will you start bloody running?' the man said.

He didn't need to ask me again.

We took off again, cutting down another road, with the panic binding me tighter and tighter the further we went. The fear was ballooning inside my chest with every second of the chase, threatening to burst through my rib cage and tearing every single breath to shreds. Just when I was starting to believe the nightmare would never end, we turned a corner and I suddenly realised exactly where we were.

Addi's car sat at the end of the road, still waiting in the exact same spot that I'd left him.

Letting go of my hand, the man flung the bag into my arms. 'Go now,' he ordered. 'Don't stop for anyone, no matter what, okay?'

'W-what?' I stuttered, as he turned back in the direction we had come. 'You're leaving me? What about that thing?' My voice sounded more screechy than I'd intended and he winced, his face rippling with irritation and his fists clenched as he looked back at me.

'Why don't you just let me worry about that, yeah? Now get in the fucking car and just go, will you?'

There was so much rage there then, so much furious heat, that I recoiled instantly, stumbling backwards, still clutching the bag to my chest. For a moment, I had visions of him raising his arm, of forcing the air at me, like he had done to the other guy in the alley, because the anger I saw in him now was exactly like what I had seen in him then. I could even feel it, rolling off him in torrents and suddenly, my mysterious hero became something darker, threatening.

Clear crystal clarity hit me hard.

'I remember you,' I said, stunned. 'From New Year's Eve...'

It was him. The one who'd watched me as I'd fallen. The one whose face I'd seen as I'd slipped into the darkness.

'Do you have a bloody death wish or something?' he snapped.

He stepped forward, a tight coil of fury, and the air around him blurred, seeming to fold in on itself and without another word, I turned and fled, only looking back when I finally reached the car.

He'd gone.

Addi, who must have seen me running towards the car in the mirror, was already getting out, his 9mm Baikal pistol grasped in his hand, held tight against his thigh.

'Case, what the fuck?' he said, but I motioned quickly for him to get back in the car.

'Get in,' I gasped. 'Get in and bloody drive, Ads.' Grabbing the handle of the car door, I threw myself into the passenger seat, shoving the bag into the footwell and desperately pulling on the seat belt.

Addi was already in the driver's seat, hitting the ignition and slamming his foot down onto the accelerator and the car screeched away from the kerb in a furious spin of tyres and smoke.

'What the fuck is going on?' He glanced down at my feet. 'And where are your shoes? Case, what the Hell happened back there?'

'I have no fucking idea, Ads,' I whispered, my hands trembling. 'I really have no idea at all.

I grabbed the pistol resting between his thighs and gripped it tightly in my lap, glancing back through the rear window and checking the side mirror as London sped by in a furious, kaleidoscopic whirl.

Same streets. Same people. Same city life. Everything was just the same as it had always been.

And yet everything had changed.