A rat scurried down the handrail at Charing Cross, its whiskers twitching as it managed a far better job than we were of navigating what had once been the escalators and what was now a treacherous mountain of twisted metal, rubble and corpses. Unperturbed by our presence, it sped past us, out of reach of the flashlights on our rifles and into the inky blackness of the tunnels below.

It seemed fitting to me sometimes, that the human race had been forced into the tunnels under the city, living out a subterranean existence in the shadows alongside the rodents and bugs.

There was a part of me – the Evie who was born after Tom died – that couldn't help but feel we deserved this. The years before had been plagued with this sense of impending doom, almost as if we had been hurtling backwards, rewinding the progress of civilisation to something dark and feral. Of course, I wasn't really suggesting we'd deserved what the Greys had done to us, but it still felt like some kind of twisted retribution for a failure to keep turning the wheel.

The old Aldwych Station, where we had set up house – albeit temporarily - had been closed since 1994, long before the Final Wave, and at one point had been a popular museum for tourists and used as a location for filmmakers. Now, both entrances had been all but destroyed and there was no way to reach it from the eastern side where the tunnel had collapsed before it could reach Holborn, which meant our front door was a concealed entrance no bigger than a crawl-space all the way over at Charing Cross.

Getting in and out of Aldwych was an adventure all of its own and the reason why Jace had been pretty close to the truth as to why the stiches had split on my wounded shoulder. If the thirty-foot of crawl-space and the escalators weren't enough to contend with, there was almost a mile of track to walk in the pitch-black tunnels where it reeked of death and rotting things.

'Shit, man,' hissed Gav, keeping his voice low, as his foot slid on loose rubble. 'I swear, I can't believe I used to complain about these damn escalators always being out of action. I'd give anything now to walk all the way down one of these without almost killing myself.'

'To be fair, it's probably easier now than back then,' Abby replied, her flashlight illuminating the way ahead, 'far less tourists getting in your way.' She'd reached the bottom, the sweat peppering her brow and sticking the shirt to her back proving that, despite her joke, it was certainly no easier journey than it had been pre-invasion. 'The only problem now is that they're under your feet instead of in front of you.' She nudged at an exposed leg, the bone protruding just below the knee, pushing it back under a pile of bricks and a mould-spattered copy of the Financial Times.

'Cheers, Abs,' Gav said, using the handrail as support and jumping down from the bottom where the last few steps cut away into a mass of molten metal and jagged edges that wouldn't have been out of place in the Tate Modern. 'Always love being reminded of the new trend of interior design we've got going on in here. Nice one, thanks.'

Abby grinned humourlessly. 'At your service, as always, Superstar.'

Gav sucked his teeth and rolled his eyes. The Superstar tag was a running joke between him and Abby, but I knew he didn't really mind it. In the Old World, Gav had been a pro-footballer, a rising star in the Premier League. I'd never been that much into football myself, but even I had heard his name and knew who he was when I first met him. Back then, he'd been a mess of arrogance and self-obsessed privilege, typical of that cocky underclass – a poor-boy-done-good who'd been dragged up on the streets of Lewisham by a single mother, only to suddenly find himself with more money than he knew what to do with. The New World had left him bitter, and sometimes, I thought, more distraught at losing his dream and all that had come with it, than he had been at losing every single person he knew. Since then however, harsh reality had bounced him off the walls and the hard-edges of his privilege had softened a bit, but he could still be an arrogant little shit sometimes.

Abby helped to roll out those last remaining touches of arrogance whenever they appeared. Almost twice Gav's age, she had become a sort of mother-figure to him, and her experiences in prison and on the streets, helped to ground him whenever his star-status re-surfaced. I liked Abby. She was hard, resilient, honest and had been through shit I didn't even want to imagine, but sometimes she got too close – or at least, tried to – and I had to push back on it and keep my distance. The ex-con and ex-sex worker was too intuitive for her own good, and I always got the sense that she knew I was only telling half the story about my past.

I followed not far behind Gav, resisting the urge to look behind at Jace, who had hung back to act as look-out as we snuck in the Charing Cross entrance. We hadn't spoken since we'd met Gav and Abby, and had to explain one, why the Hell we'd taken so long and two, why we were both splattered in blood. I'd stayed silent throughout much of the exchange, still reeling from what I'd done and still disturbed at the thought of Tom's killer's presence in Quadrant Two not being a coincidence at all.

I could tell my actions had stunned Jace, and as we carefully climbed down the escalator, I could feel his gaze burning a hole in my back, the weight of his troubled thoughts resting heavy on my shoulders. Not that I could blame him. Having your mate blow a Grey's brains out right in front of you with no warning is bound to unsettle anyone, especially when that Grey probably could have been persuaded to offer more information about their infiltration of Lena's crew and what happened to them all. Now, we'd most likely never know, unless we happened to find Lena for ourselves and after discovering Rico hadn't really been Rico after all, I knew I'd destroyed any chance of that when I'd put a bullet in his bastard head.

Reaching the bottom, I jumped down, feeling the tug in my shoulder and a loosening in the skin, which probably meant a few more stitches had torn. Abby swung her torch near me, as I pressed my palm to the wound, her worried gaze making me look away. I couldn't deal with her concern today or the way she often looked at me as if all my secrets were laid bare on my skin.

'You need that looking at,' she said, brushing wisps of her ash-blonde hair off her face, 'we'll go see Ivy as soon as we get back. She'll get it stitched up again in no time.'

Jace climbed down from the escalator and, I noticed, kept his eyes fixed firmly on everything butme. A creeping unease settled deep in my stomach. His withdrawal felt like a punch to the gut, almost as if he'd raised the barrier again, the one he'd built around himself before he'd joined Taj and the rest of us. I mean, sure, I'd constructed a barrier of my own too, because of what had happened with Tom, but I think Jace and I saw something familiar in each other back then and our connection had formed easily. I couldn't bear the thought that I'd ruined that now, that I'd let Tom's killer come back into my life and wreck everything all over again.

'Okay, let's go,' said Jace, his SA80 at the ready and we all followed suit, picking our way carefully through the rubble until we reached the platform. The tube tunnel stretched ahead of us, the entrance like the mouth of some great beast waiting to swallow us whole.

I'd walked this tunnel countless times over the past couple of months, but I still felt those familiar twinges of dread whenever we had to journey through it. Pre-invasion, I'd have probably been more terrified about the rats and the spiders that were so bloody big you'd have been excused for thinking you'd just wandered into some pre-historic King Kong-like valley where the bugs were bigger than your head. These days, I paid them little attention. It might earn you a bite or two but having a tunnel spider crawl up my neck was preferable to encountering a Grey squadron who could climb the walls better than any spider or rodent.

We cut the conversation now, focusing only on the mile of tunnel ahead, the beams of our torchlights penetrating the oppressive gloom and criss-crossing as we swept them over every surface. Miraculously, we'd never encountered Greys in this tunnel, but the memory of previous attacks was an ever-present nightmare none of us ever wanted to experience again. The New World had brought with it many unpleasant surprises, but sweeping your light up overhead, only to see a swarm of Greys, soundlessly crawling along the roof of the tunnel towards you on thin spindly limbs, their black eyes glinting in the torchlight, was probably the one that had spiked the most fear in my gut. Of course, that wasn't including Rico and the Shaftsbury Theatre, but Rico was dead now, as hopefully were the secrets that he'd carried with him about the Grey who'd tortured him.

My skin prickled at the thought of Tom's killer out there somewhere, watching me, and I instinctively turned back to face the other way, arcing the direction of my flashlight slowly over the tunnel behind me. Nothing but the sharp eyes of the rats reflected back at me in the darkness.

'You hear something?' Jace said, moving close to my side.

I waited, trying to pick out movement, wishing I could shake the cold touch of paranoia that was haunting me. Finally, I shook my head.

'No. I'm just... tired.' Paranoid. Freaked-out. Losing my fucking mind. 'There's nothing there. Nothing at all.'

Jace hesitated, his shrewd eyes scanning the tunnel, his steady arm holding the rifle as he checked almost every inch of shadow. Double-checking what I'd already done. When he seemed satisfied, he moved past me, avoiding my gaze, the barrier back in place once more.

I stood for a few seconds, watching as the gap between us widened and as the beam of their flashlights and sound of their footsteps rounded the bend ahead.

Tell them, Evie. Tell them before it's too late.

I willed for a sound then. Just one, tell-tale sound in the gloom. One creeping shadow too big to be a rat. Anything that would prompt me to open my mouth and let the secrets come spilling out.

But nothing happened and I remained silent, following the others and letting the secrets swallow me whole again, before the darkness could.

*

'I told you, child,' Ivy said, her head tilted back so she could peer through the silver-framed glasses perched on the end of her nose. 'What did I tell you? But did you listen?' She pursed her lips. 'Uh-uh. No, you did not. I told you not to go out for a while or you'd be busting these stiches right open and now look what happened. All my painstaking needlecraft gone to waste.'

'Well, you did say you wished you could take up embroidery again.' I closed my eyes to the stinging pain of her needle and gripped the back of the chair harder.

Ivy tutted close to my ear. 'I meant, I wanted to embroider eiderdowns. Cushions. That type of thing. My dear, I have no wish whatsoever to embroider your skin. Especially when I've already completed the job first time round. You make me look like a poor seamstress who can't sew a damn thing.'

I winced as she pulled the suture tighter. 'I doubt anyone is questioning your workmanship, Ivy.'

'I should hope not,' she said, the Jamaican lilt in her voice growing stronger as she protested against the indignity of anyone possibly doubting her abilities to sew up a wound. Ivy had probably sewn up more wounds since we'd been housed up in Aldwych, than she'd embroidered cushions in her whole life. 'Although, they'd do better to doubt your intelligence, girl, which would be a shame, because I never had you down to be stupid. You want to talk it over?'

The sharpness in her tone softened then, the warmth she seemed to have in endless supply making me keep my eyes closed because I didn't want to look into hers now and see the same suspicion and doubt that I had seen in Jace, Gav and Abby's.

'There's nothing to talk about.'

'You shot Rico in the face.'

I opened my eyes then, to find her looking at me over the top of her glasses, one dark eyebrow raised, lips pursed again, the lines around them deepening.

'Now, I don't know about you, but I happen to think that's a damn sight more interesting topic to talk about, than the fact Vik swears he saw a crocodile over in the Fleet culvert up by Holborn.'

She fixed her attention back on the needle, her tongue clicking against her teeth as she threaded it through my skin once again. She was wrong about anyone thinking her a bad seamstress. Her work was always meticulously neat, if not painfully time-consuming.

'Vik saw a crocodile?'

Ivy rolled her eyes and exhaled in a big harrumph. 'Oh please. That man is a damn fool. He didn't see no crocodile.' She leaned in a little closer and winked. 'If I didn't know better, I'd say he was the one who swiped the liquor from the storeroom.'

I held her gaze for as long as I could bear, shooting her a small, nervous smile. She grinned knowingly as she put the needle to one side and tied a square knot to secure the surgical thread. Before I could move, she laid a hand on my own. It was warm and soft and for a moment, I felt a catch in my throat and had to swallow it down.

'You know, there's no shame whatsoever in admitting you're scared,' she said. 'No shame in admitting this new world of ours is grinding you down. And there's certainly no shame in putting a bullet in a Grey's head because it did you so wrong that you had to drink yourself into oblivion to forget it.'

I gripped the chair tighter but still she didn't let go.

'That creature tried to defile you in the worst possible way. But you know what? I don't think it's that which has got you running scared.'

Stop it. Stop talking. I can't.

'I reckon it was because for the first time in a long time, you were alone. For those few minutes, on that stage in the dark, you were alone again and that terrified you right down to your very bones.'

On the wall opposite, there was an old TFL staff noticeboard, where someone had scrawled the date and time for the next staff briefing – a meeting that had never taken place, because by then the Greys had arrived in force, their crafts crowding the skies, their army infesting our streets. Underneath the date and time, in capitals, it read DON'T BE LATE!

I nodded in the direction of the board. 'I wonder if Eric died alone.'

'Eric?' Ivy's face crinkled with confusion.

'Eric. According to that notice, whoever Eric was, he was meant to bring the biscuits for the staff meeting. I wonder if he died alone or if he's out there somewhere, pumping bullets into Greys that deserve to be killed without a second of hesitation.' I turned my gaze towards Ivy. Firm. Resolute. 'Rico deserved it. I don't care what anyone says. I'd do it again in a heartbeat.'

Sighing, Ivy withdrew her hand and began tidying her medical supplies away in the small green plastic case. 'Okay, child. That's okay. Sometimes we gotta hold on to whatever story we tell ourselves, just to get us through a long night.'

She stood up, rubbing her hip and wincing a little as she moved to the counter on her right, sliding the case back into the open cupboard, which she shut and locked using the small key that she kept on a chain around her neck. She'd been locking it ever since Stephen gorged himself on the morphine supplies and had crawled into the train carriage that was stabled on the tracks just before our Aldwych base and waited to die. Abby had been the first to find him, curled up in the corner of the coach, his body stiff but still warm to the touch, his face free of the utter desolation he'd been wearing like a mask for so long.

'We're all alone, Ivy,' I said as I got up, sliding the chair back under the table. 'Every single one of us. It's whether we choose to let it beat us or whether we choose to fight back and win.'

I moved towards the door, but Ivy's voice stopped me in my tracks.

'Just out of interest, Evie, love,' she called out. 'Do you feel like you're winning the fight?'

I glanced back over my shoulder at her. Ivy had always been my go-to person, ever since I'd joined with Taj and the others. She was a go-to, not just for her medical skills learned from her many years working as a nurse after she came over on the Empire Windrush, but for her stories, her wisdom, her knowledge and a soul that kept you bathed in hope, even when life seemed the bleakest of all. I hated the thought that I couldn't wait to get away from her now, that I needed to escape from the one person I always sought out whenever I needed a soft hand on mine and a smile that reminded me what is was like to feel homesick for the Old World.

'Revenge is a bittersweet thing, Evie. It might feel good at the time. In fact, it might feel like the best damn thing you ever felt, but it has a nasty habit of turning you sour, child. Don't let it harden that heart of yours. It's our hearts that make us human.'

I rubbed my thumb over the space on my finger where my wedding band had been and felt the ghost of Tom press his cold mouth against my neck.

'My heart died when the Greys came, Ivy,' I said. 'Revenge is all I have left now.'

Ivy looked at me again over the top of her glasses, the weight of her years suddenly shrouding her face in an exhaustion that scared me a little.

'Oh, child, then you ain't winning nothing. You ain't winning at all.' She tutted and shook her head, wearily. 'You better go see Taj. Let's see what he thinks of your great story of revenge. Somehow, I don't think he's going to like it very much.'

I scraped my teeth over my lower lip and shot her a small smile.

'Well, at least that's something we can both agree on,' I said and pushed open the door into the narrow corridor beyond, steeling myself for the next fight.