Taj Varma, leader of our ragtag group of survivors - a mixture of the physically competent and the just-plain-fortunate, or unfortunate, depending on your point of view – was talking in low, hushed whispers with his brother Vik, when I found him in the old manager's office.

Despite there being just two years between them, the differences between Taj and Vik couldn't have been more vast. If Taj was the human equivalent of an Olympic Gold Medal, Vik, was a plastic five-a-side football trophy which had lost most of its plating and had been chucked in a box destined for a car boot sale.

Vik was the older of the two, short, balding, and had a tendency to sweat profusely, but fortunately had been blessed with the trademark Varma teeth that would have been good enough for a toothpaste commercial, even if the rest of him wasn't. He had also worked for TFL before the Greys came, and it was thanks to him, that we had managed to locate the secret TFL rooms hidden away beyond the train platforms and collapsed tunnels.

Taj, on the other hand, had been a flashy banker in the city before the Final Wave. Weirdly, he was probably one of those blokes I would have disliked with a passion – a smarmy city-boy with his flash suits, a nice car, a bloody great apartment with a desirable balcony view, and more irritating fast-track patter than a real estate agent on amphetamines.

Taj had lived the life. Not a superstar life, like Gav, but definitely a life that I couldn't have identified with, even if you'd suddenly given me a shit-load of cash and thrown me slap-bang into the cosmetic surgery chaos of Knightsbridge. Not only was Taj a wealthy banker (successful fella, city dweller, sings Tom), but he was also an adrenalin junkie, one of those mad bastards who spent their weekends hanging off the side of a mountain using just their mega-strong index finger or jumping out of a plane, ingratiating Instagram with one of those super-annoying thumbs-up-aren't-I-just-living-my-best-life selfies that made you want to throw up in your sad little microwave meal for one.

Ironically, it was that fake James Bond wannabe lifestyle that had given Taj the strength and determination to survive and, I had to admit, he was a highly proficient leader of the group. He had a strategic mind to rival even that of Jace's, was a skilled fighter and strangely, for a banker and former Insta-addict, was also a really good listener. Everyone in the group trusted him implicitly, which I always found interesting since I knew Taj had a secret.

A pretty bloody big one at that.

A secret that only I knew.

Taj rarely cracked under the burden of the New World, but the one time he did, I just happened to walk in at the wrong moment, ready to talk to him about how someone had been raiding the rations – there's only fifteen tins of beans, there should be sixteen, or something banal like that – and finding him with his face pressed against the wall, the stifled sobs wracking his whole frame.

An insistent declaration of just having a weak moment, turned into a confession I never expected in a million years, and, it turned out, meant that Taj and I had a connection that I never would have expected in a trillion years.

Taj's boyfriend, a model called Arturo, had been a Grey. Or, at least, had been killed by a Grey, who had then assumed Art's identity and had lived with Taj for the best part of a year before they all unmasked themselves and started the great invasion ball rolling by killing those they were closest to.

Only, Arturo, hadn't killed Taj. He'd let him go. Unable to fathom just why the Grey had spared him, Taj had done what he always did best: survived.

He was still surviving now, and I was the only one who knew his dirty little secret – his weakness – because not only had Taj not known he'd been effectively shagging an alien for a year, but it had been the best year of their relationship. It was the year of mad, all-consuming love. It was the year they talked about getting married. It was the year they planned a future together, away from the rat-race, away from the Insta-ready fakery and finding something real and tangible, maybe in the Italian countryside.

Taj, with a shame that had broken his voice into a hoarse whisper, had admitted he had loved Art with every fibre of his being. He'd loved him, even though he'd discovered he was a Grey.

'How could I, Evie?' he'd said, the disgust twisting his face. 'How could I have loved one of them?'

He'd spat out that last them with a vitriol I wasn't accustomed to from Taj. He was level-headed, emotionally-balanced, never once displaying the poison of hatred that had affected so many of us.

I could have told him about Tom. I could have confessed everything, from the moment of Tom's murder to everything that came after. The incessant questioning from the police. The accusatory looks. The suspicion. The total disbelief. How I'd been branded his murderer, and then, finally, a crazy person who'd lost her grip on reality with talk of Grey men with black eyes. How I'd become estranged from everyone I had known. How I'd lived life as a ghost, unseen, invisible, hiding away in a house that felt haunted, not by me, but by Tom and my memories. How my life had collapsed until I hadn't wanted to live anymore.

I could have told him, and maybe, just maybe, it would have offered Taj some small iota of comfort to know he wasn't alone.

But I didn't. I'd nodded dutifully when he asked me to keep his secret, but I never gave him mine. I never gave anyone mine.

Despite knowing I'd always have that secret over him, should I ever need to use it, I still hesitated in the doorway, not liking the way Taj's forehead crinkled into a frown when he looked over and saw me.

He motioned me over with a smile that didn't reach his eyes and exhaled a long sigh as he combed his fingers through his dark hair, pushing it off his face and using the band around his wrist to tie it back into a loose ponytail.

'Uh, hey Evie,' Vik said, shuffling from foot to foot as I approached, and blushing as if I'd caught him with his hand in the store cupboard. There was a line of sweat just above his brows.

'Hey, Vik.' I stopped in front of Taj but kept my eyes on his brother for now. 'How's the crocodile?'

Vik scowled, his bottom lip protruding like a sulky child. 'You've been speaking to Ivy, I bet. I swear to you that I definitely saw it. I don't know why no one believes me.'

'You never know, Vik,' I said, not wanting him to think I'd been laughing at him behind his bag. He was a good guy, plastic football trophy or not. 'It's plausible. They had a Philippine crocodile at London Zoo. Maybe it got out and has been living in the waterways?'

Vik's face brightened instantly. 'That's exactly what I said too!' He turned to his brother, looking vindicated. 'See? I told you. We saw the lion that day. No reason why the crocodile couldn't have escaped too.'

'Sure. Maybe they eloped together?' Taj teased, the warmth creeping into his expression.

'Impertinent little shit.' Vik punched him on the arm, playfully. 'He always was, Evie. Right from the moment he could open his mouth, he always had something smart to say. Pappa and Mummy couldn't shut him up. Mummy even tried to keep feeding him up with mountains of mithai to keep his mouth busy.'

'Which didn't work because you were the one that ate it all. I could barely even get a sniff of it.'

Taj glanced at me and the tension that had lifted with their familiar, easy chat came down like a lead blanket again.

'I'd better get going,' Vik said, instantly picking up on the vibes. 'I need to check out that cave-in over on the East tunnel.'

I watched as he walked away, hitching up his jeans at the back which always had a tendency to slip down. I made a mental note to try and find him a new belt on our next looting mission.

'There's been another tunnel collapse?' I asked Taj, as he moved over to where the TFL blueprint tube map was tacked to the wall, marking off a section in one of the tunnels with red marker pen. The Eastern tunnel was becoming a concern. It was dangerously unstable, with more sections of the tunnel collapsing every week.

I hated it here, always had. Not because of the death-saturated tunnels or the TFL rooms where the stench of coffee and stale cigarettes still lingered strongly, but because it seemed like a dead-end to me. There was only one way in and only one way out and there was something about that which didn't sit right in my stomach. I needed an exit. I needed to know I could run and keep running and eventually I would hit air and daylight and at least know I could do something. But even I had to admit we'd been safe here. It was a long way from the Ritz, the Dorchester and even a two-star flea-infested bed and breakfast in Soho, but so far, it had remained pretty secure away from the searching black eyes of the Grey death squadrons. The closer the cave-ins got to our base, the more likely it was going to be that we'd have to move on and find somewhere else before the whole of Aldwych collapsed on top of us.

'Yeah,' Taj replied, stepping back and studying the map. 'About another fifteen metres or so went down. Vik said there's nothing on the surface to indicate why. The buildings are remarkably intact. My guess is we've just been lucky it's held out for so long.'

I could see prospect of what was coming our way weighed heavy on him. If it was just a case of moving the likes of me, Jace and the others, that wouldn't have been so bad, but there were thirty-six of us down here including four kids under the age of ten and then there was Ivy to consider. Her mind and eyes might still have been sharp as a tack, but physically, getting her out of here wasn't going to be easy. Hell, getting her in here had almost killed her.

Clicking the lid back onto the marker pen, Taj stuck it to the wall using a big blob of dirty blue-tack, before turning to face me, leaning against the edge of a desk in a move that reminded me of a school teacher about to deliver a long and painful lecture.

'Before you say anything,' I said, taking a breath and reeling off quickly, wanting to get in there before he started talking. 'I know I lost it out there today and I'm sorry. I made a mistake. I let my emotions get the better of me and it won't happen again. I know I fucked up.'

'Fucked up would be an understatement.'

I winced inwardly at the sting of his rebuke and even more at the hard look in his eyes.

'We could have used him.'

I scraped my teeth over my lower lip and felt the guilt swamp me. 'I know, Taj. But the chances are he wouldn't have told us anything anyway. The guy was a piece of shit.'

'A piece of shit who could have been coerced into giving us some information, no matter how small. And yeah, maybe he wouldn't have said anything. Maybe he would have told us to go fuck ourselves, because that's the type of cûntish thing Rico would have done, but we'll never know now, will we, because you decided to blow his brains out.'

Taking a step back, I balled my hands into fists by my side, digging my nails into the palms of my hands in an effort to hold onto my nerve.

Taj's face softened. 'Evie, look, I get it, okay? What Rico tried to do to you was...' He floundered, failing to find words that I so easily could have provided for him.

Horrific. Terrifying. Invasive.

'It was fucked up. I know that,' he continued. 'And I know it hit you hard. But today shouldn't have been about you and maybe that sounds cold. In fact, I know it does and I'm not saying he didn't deserve everything he got and more, but we needed him, Evie. We needed him. All of us. You can't let something become just about you no matter how much it hurts. Personally, I'd have let you have him. Right after we questioned him, I'd have let you do whatever the Hell you wanted to him. I can't have someone's personal agenda taking priority over the group, you know that, right?'

He sighed again, pulling his ponytail tighter before rubbing his palm over his mouth.

'Evie, you're one of the best we have, but I've got to be able to trust you'll always put the group first.'

My eyes widened 'Christ, Taj, you think you can't trust me now? I've already admitted I know I fucked up. It was a blip, that's all. A moment of madness.'

'Moments of madness and blips will get us killed and we've fought too long and too hard to let that happen. You know that more than most.'

'Yeah, I do know that,' I said, my voice harder now. 'Because I've been a part of this group pretty much every step of the way. I've fought for this group. I've risked my life every single time I've stepped out of this place. Everything I have done has been for this group and you know that. I screwed up today and I'll be the first to admit that, but one screw-up shouldn't mean you stop trusting me.'

'I'm not saying I don't...'

'Yes, you are.' I clenched my fists tighter. 'We all make errors of judgement, Taj. All of us. Even you.'

Evie, you bitch. You had to go there, didn't you?

Taj slicked a tongue across his lips and eyed me steadily. 'I'm aware of that. We all make mistakes. We've all done shit we're not proud of. And yeah, we'll all fuck up once in a while because we're only human, but if the Greys had managed to infiltrate Lena's crew then we needed to know everything and anything we could squeeze out of Rico. Sure, maybe we'd have got nothing from him. But we might also have got something. Even one little bit of intel might have helped, who knows?'

He trailed off, his gaze sweeping over my freshly-stitched and dressed shoulder wound.

'How's that going to hold up?'

I gingerly touched a hand to it. 'Ivy's fixed it pretty good,' I said, omitting to tell how she also thought I should take it easy, but I knew she'd told Taj that when it first happened anyway, and no doubt would again. 'She's got some mean skills with a needle and thread.'

Taj nodded and folded his arms across his chest. 'She certainly has. And you've got skills we can't do without. I meant what I said, Evie. You're one of the best we have and if I'm being hard on you here, it's because I'm fucking terrified of losing you.'

I looked at him, crestfallen and feeling even worse about using his secret against him. 'Shit Taj, you're not going to lose me.'

'Then don't pull stupid, thoughtless crap like this again, okay? I need you to get your head together. The Rico shit is done. There's nothing we can do about it now. But you've got to forget what happened and put it behind you. The group comes first.'

'I know.'

He pursed his lips together, his eyes narrowing. 'Good. I hope so. Jace, Gav, Abby, Lenny and I are going over to Lancaster House tomorrow and I want you to come with us.'

I jolted. 'Lancaster House? Taj, that's dangerously bloody close to the Palace.' 

Dangerously close to the Palace and right on the edge of Quadrant One.

Quadrant One was a no-go zone. It was their zone. The Greys.

Of course, everywhere was theirs now, but their presence was still hugely concentrated in Quadrant One, having taken over whatever was left of the main government buildings in Whitehall and the Royal Residences of St. James and Buckingham Palace.

The riots had ravaged Whitehall in particular, before the army moved in to crush the protestors and the bombings that followed had decimated large parts, including much of Downing Street - even though the Prime Minister and his crumbling cabinet of ministers had long since been evacuated - but the area south of Trafalgar down to Westminster and east over to Hyde Park Corner was still theirs.

You couldn't get in, even if you were mad enough to try and while the New World had sent many insane, none of us were crazy enough yet to even think about venturing into Quadrant One.

We'd all heard the same horror stories.

Stories about humans being marched into Quadrant One. Stories about how the Greys weren't just here to kill us, but to harvest us. For what, we still had no idea, but Lena's admission that she'd seen hundreds of captured men, women and children, being taken into the Black Zone had put paid to any notion that the Greys were here simply to conquer Earth and wipe us out. They needed us for something else. Another horror to lay upon the horrors we had already suffered.

Taj stared hard at me. 'I know and I wouldn't send anyone that close if I didn't think we desperately needed to go.'

'So, what's at Lancaster House?'

'The company Lenny worked for had a contract there a couple of years ago. They did some renovation work in the basement. Did you ever hear the story of the wine cellar?'

I shook my head, wondering whether Taj had gone mad after all and was planning on getting us all killed because he wanted to get his hands on a few more bottles of expensive booze.

He grinned. 'Turns out, it was the government's secret £2million wine stash, only Lenny says vintage plonk wasn't the only thing they stored down there. There's another cellar where they stock-piled medicines and food, meant for dear old Lizzie and her royal brood should we all end up in some kind of World War Three situation or a zombie apocalypse or something. The second cellar is top secret, classified info only known to top government officials, and, as luck would have it, a Lancaster House staff member who went by the name of Violet and who took a particular shine to our handsome bit-of-rough Lenny when he was working there.'

I exhaled a low whistle. 'And he's certain about this?'

'One hundred percent. Saw it with his own eyes after privately-educated Violet Conroy-Hills took him down there so she could have a little taste of a commoner without mummy and daddy knowing.'

He rubbed at the back of his neck, the tightness around his eyes showing an exhaustion I rarely saw from Taj.

'Like I said, I wouldn't even suggest going there if we weren't in urgent need. You've seen the stores, Evie. Pretty soon we're going to run out of supplies. Now, I don't know if anything will be left or whether the world fell apart so quickly that Lancaster House's secret cellar was forgotten about, but I reckon it's worth a shot. We're running out of options.'

I glanced over at the tunnel map on the wall, where the highlighted red section of destroyed tunnel seemed to glow even brighter, like a giant fuck-you to any hope we might have been harbouring that we'd survive this for much longer.

Taj was right. Supplies were dangerously low, as were the choices available to us.

'Well...shit,' I said, before remembering Jace's reaction earlier. 'Is everyone else okay with me going?'

Taj levelled his gaze at me.

'I do trust you, Evie.'

My stomach dropped. 'That's not what I asked.'

Taj's hesitation was all I needed to know. He might claim to trust me, but I knew Jace didn't. Not anymore.

Taj reached out and touched a hand to my good shoulder.

'I trust you,' he said. 'You get back out there tomorrow and show the others they can trust you too. They need you, Evie. We all do. It's up to you how this all plays out now. You just need to promise me that you'll never pull a stunt like today again.'

I remembered the graffiti written in blood. The alien symbol carved into Rico's chest. Tom's eyes meeting mine across the ruins of Piccadilly.

Not Tom. Not Tom.

'Promise me, Evie?'

I smiled at Taj, wondering if my smile would have been convincing enough for his living-my-best-life Instagram gallery. I hoped so.

'I promise,' I said.