There was a night a few weeks ago when my brothers and I arrived here for what should have been an easy mission. My brothers were attentive but unworried, joking, whispering discussions not just of the upcoming night but of our interests, our plans for the next few days, what we had done apart, what we could do as a group. In short, while we waited for true darkness and the moment we could take back our DNA from Bishop, we behaved as we always had done; as a family.

The sky looks the same as it did that night. Purple like a bruise, fading to black. Fitting.

This time, I am alone.

The father we had left at home is dead now. No one there for me to return to. My brothers are not with me. One of them is dead, his body stolen for who knows what vile experiments. Stolen by our brothers.

I wonder what became of the one I left back at the lair. He was trying to trick me right until the end, right until I had to run before the whole place I called home was destroyed. He would have run of course. He probably warned Bishop right away, Bishop will be expecting me. It bought some time for the body of my dead brother; it means I might get him back before they cut him open, abuse him even more horribly than they have already.

No matter what they want me to think, I know he died because of me. They might have done it, but it was because of me.

I've lost them all. One of them through death, the other two through their betrayal, through their actions. They may as well have died, because I no longer have three brothers. I am alone.

Bishop's building lies ahead, seemingly no different to a hundred other uniform buildings of the same era. It's more isolated than some due to the nature of what occurs within its walls but that works in my favour. Splinter was right. No one must ever know of our existence and some of the things I have planned for that place, what I'm going to do as I leave with my brothers body on my back, will attract attention. But I hope that I'll be long gone by then.

Maybe one of the two who betrayed us will be called to take his place. But I can't worry about that now. That would be a waste of time. If they're cold enough to do all that they did just to get to me, then they'd have no worries leaving me in the clutches of our enemies. I can't let myself pity them or it could be the end of me.

The last time I was here, I knew nothing of this. I was secure in the love my family had for me and the trust that I had for them. Now everything is turned around. That love didn't exist and I couldn't trust them at all.

It's a bitter pill to swallow as I watch the purple bleed from the sky until darkness comes.

True darkness. Time to act.

I stretch my body to work out any kinks I might have from sitting still a long time, something I always do out of habit. Then I drop to the ground silently, avoiding the alarms. I could easily disable them, but if my treacherous brothers have told Bishop to expect me, that would be like lighting a neon sign saying, I AM HERE. Let them wonder a while longer.

The grounds, no doubt littered with traps, few places for shadow. But I have been ninja my whole life and manage without too much trouble. It's the same route that we – the four of us – took the last time. I know they know that I'm too smart to take the same route so if I do then they won't be expecting it.

I just can't believe it came down to this. Betrayed by my own brothers. Sold off to Bishop.

I wonder if he really was catatonic?

But that was all that he wanted me to think and it could distract me. Have to remind myself he faked it. He wasn't hurt. Wasn't out of it. That glassy look and the fixed stare, that was just a part of his scheme.

Wasn't it?

No, I can't let myself be distracted. I have to focus, I have to get my brothers body back because…

I realise there's someone beside me a second too late to avoid the blow to the side of my head, that has me immediately seeing stars. But I recover, rolling away from the assailant, unconcerned with discovery now it looks like I'm too late and my presence has been found out. I'll just have to fight my way through this time and back out again. There is no way I'm letting Bishop use either of us, even in death.

I complete the roll and spring to my feet, hand going to my back to retrieve my weapon. I don't even pause when I realise who the assailant is. The tails of his bandana stirring in the breeze, the weapons clutched tightly in his hands, the hatred in his eyes, the sneer on his mouth. The traitor I last saw fleeing the lair to bring the corpse of my brother here.

"I knew you'd come,bro," he snarls, taking a step toward me. "I figured it out, soon as I worked out who gains from selling us out to Bishop!"

I shake my head, prepared for his attack. We've been sparring together for years and I know just what to look out for. He's strong, he's obsessive about training in a way I never have been – but he's reckless, impatient, emotion-driven. I can use that, just as long as I never forget that he knows a lot aboutme too, how I fight, where my weak points are. My best chance is in goading him into forgetting them.

But the strangeness of his words doesn't escape me either.

"Gains? Gains! I lost my whole family, my brother, my father – and you two sold us out…"

He interrupts like he doesn't even hear me. "I should have known you'd give us up in a second for your damn research – I didn't believe it, I couldn't, but I guess…"

He breaks off and a grin breaks out across my face. Now I know what he's doing! Trying to play head games, make me angry. Let him try. He's not as smart as me, not smart enough to know what he's doing. I can see right through him. Same as back at the lair. They keep trying to fool me but I know better than that.

I take a hand off my weapon for a moment and point a finger at him accusingly. "You tell yourself what you want – but you betrayed me, you betrayed us all, and I don't even know why you did it…"

"NO!"

"You couldn't wait to bring his body to Bishop!"

"I had to protect him from you!"

Just as I predicted, he leapt at me and even though I knew it was coming, he was so damn fast. I've had him go for me at that speed before, but before now I always knew – or at least thought – he wasn't going to hurt me. Knowing now that he's after blood, that the look of rage on his face is directed at me, it's more terrifying than I would have ever imagined.

Still, I don't lose my head. His weapons are aimed at me, so I bring up my own weapon and when he hits the downwards arc, he crashes right into it. The look on his face is comical and I smirk as I flip him over my head, the sound of metal against the ground telling me that at least one of his weapons has skittered out of his grasp.

No time for self-congratulations. He landed heavily on his shell but he's already getting to his feet as I flip backwards. I swing, trying for a knockout blow on his skull but he's on his knees and catches the weapon before t can land, stopping its progress. I can't defeat him in a battle of strength but for a moment my instinct tells me to struggle for possession and it might just have cost me big as he uses my attention on that to take my feet from beneath me. The weapon flips away from both of us as I land, kicking at his legs to knock him off balance again but succeeding only in bringing him crashing down on top of me.

Ninjitsu be damned. The battle turns into an all-out brawl. Damn, I always knew he could hit hard but there's a real malice in the act this time. A vicious shot between plastron and shell knocks the wind right out of me and makes me feel like vomiting. But there's no time for that, no time at all. He hits me over and over again, bruising my skin, even managing to leave scratches on me.

I shove him back and succeed in rolling on top, slamming my hand into his forehead and cracking his head against the ground. That must have hurt, but he's a tough bastard and doesn't even flinch. Instead he brings his head straight back up, butting me right on the snout. My eyes involuntarily tear up and blood starts gushing from my nostrils. He takes advantage, shoving me onto my shell and mashing my mouth with a fist, cutting open my skin and I'm pretty sure he loosened a couple of teeth. My mouth immediately doesn't feel right and with the blood and the injuries, it's getting hard to breathe.

I'm losing the fight.

Another fist lands on my windpipe and I give a harsh gasp, still fighting for breath, my arms falling outwards as I try for leverage to push myself up. No go. His weight is too much.

I feel the steel beneath my scrabbling fingers at the same moment his hands lock around my throat.

Nerve grips were never his specialty but I know enough to realise he's searching for the right pressure point to put me down unconscious. If he does, it's over. I'd wake up in a cell, a guest of Bishop. And who knows what would become of me then?

I don't know – but I've always had a good imagination and a working knowledge of medical experiments.

A split second to choose.

I realise the metal is his weapon as I grasp the handle and feel its weight – not my weapon of choice, but maybe the best in the circumstances. The best I could hope for in close and personal circumstances.

I swing the weapon, still struggling to breathe through the blood and the pain and his weight pressing onto my chest. I'm hoping to crack it against his skull, knock him out, anything just to get him off me…

Instead, the steel punches through the skin of his neck with sickening ease, sliding deep into the muscles and tissues in there, severing the jugular vein as easily as any sharper blade would have done.

His eyes widen and his gaze meets mine. He looks shocked, confused – betrayed, Hurt. And I know that the features of my own face are drawn into utter horror.

And then I become aware of the blood raining down on me, raining down the arm that still clings to the weapon, pattering onto my plastron even as his weight pins me to the floor.

I jerk backward, instinct making me keep my grip on the weapon. But there is nowhere I can go and all I succeed in doing is pulling out the weapon that had previously staunched the wound. Immediately, there is a spray of thick, warm blood and within seconds, my face is covered with it, falling into my gaping mouth, mixing with my own blood, coating my body and the ground beneath us.

His weight collapses on top of me, a body without life within.

I moan in revulsion, horror and loss, rolling him to the side and off me. He lands in the dirt and the stain of his own blood, staring up at the sky. For a moment, all I can do is stare at him. He was my brother for so long, growing up with me, looking out for me, sparring and playing with me, joking with me, helping me.

Betraying me.

And now he's dead.

"Stay where you are!"

I start as the spotlight hits me. I'd totally forgotten that he wasn't the only person I would face tonight – too emotional, too caught up in the fight.

Too bad.

Raising my hand to shield my face, I get to my feet, years of practice making it an easy task to ignore my wounds. But ignoring my brother isn't as simple. Intellectually, I know that he's a traitor but emotionally, I want to take him with me and get him away from here, even though I know there's no hope of him ever recovering. Even though it was me who did that to him.

But I have to leave him. There's still my mission to consider, my innocent brother, who deserves better, still within those walls. Let them have this one, the one who sold us out. But I won't leave my brother in there.

I run from the unrelenting glare of the spotlight, hearing the noise as the alarms start bleeping, aware that my progress is probably being tracked remotely and my every move broadcast to the guards attempting to take me down.

Strange. In spite of the noise and the lights, I can't see any actual people around. Maybe they were distracted by the body I left behind. Or maybe they have something else up their sleeve.

It's that consideration that makes me slow, reach for a smoke bomb and rethink how I'm going to do this…

And then my legs start to feel too heavy, trembling, turning traitor on me just when I need them the most. Well, why not? My brothers betrayed me, why wouldn't my own body do the same thing?

I slow, my fingers scrabbling uselessly at my belt for the smoke bombs, numb fingers coming up empty. It's suddenly hard to move, my vision seeming to swim in and out of focus. I do a mental check of my injuries, wondering what the hell that traitor managed to do to me.

The light blinds me as I give in to gravity and sink to the ground, still struggling to get into the building – but I didn't even make it to the door. And now there are two ways I can make it; either crawl in there or be taken.

It doesn't look like I'm getting a choice.

Now there are soldiers, spilling out of the building, five of them with their guns trained on me as if I were in any kind of shape to run or fight. Whatever they did to me worked too well. And I was too distracted to even notice, although there's a burning on my shoulder that suggests a point of entry for whatever drug has been pumped into my system even that could be my imagination.

I glare up at them even as my shaking arms fail me and dump me on the ground, unable to move, leaving me to stare at their boots. And Ireally don't want to move. It's been so long since I was able to rest, even though this is forced, it's welcome…

And that kind of thinking is going to do me more harm than good. Maybe there's still a chance I can get out of this. Maybe.

In my line of vision, the boots are replaced with shiny black shoes and rough hands grab hold of me, turning me onto my shell so I can see what's happening, although I still can't move at all.

Bishop stares down at me, a smirk on his usually imperceptible face.

"You were only supposed to fight until the tranquiliser kicked in," he says, as if this is some pre-rehearsed play and I forgot my lines. "We were hoping to take you both alive – well, at least we have one of you alive. And one dead. I'm sure it'll be only a matter of time before the others come searching for you – if they're still alive. That was quite a display you put on back there. You're the last turtle I would have expected it from."

I cough weakly, wanting to call him a hundred names for doing this and myself a hundred more for falling for this trap – but I have to know one thing even more than I have to berate either of us.

"What did you give them? Why – why did they betray us?"

Bishop looks startled for a second, then throws back his head and gives a real laugh, the kind that you get surprised into and then can't stop. It took him three attempts to get it under control while I lay at his feet, paralysed and not seeing what is so damn funny.

"I gave them nothing," he says once he can finally speak without sniggering. "Is that what you thought? Oh, I love what they can whip up in the lab these days. I knew that humans had paranoid delusions and fantasies when exposed to them, but I thought it would have less effect on your mutated cells – instead, an increased reaction. Perfect. Something else we can use your cells for."

Nothing.

He gave them nothing.

I turn the information over and over in my mind as the soldiers grab me without any pretence at care, dragging me onto a gurney and rolling me into the building, where presumably the drug they have given me will wear off only after I am safely locked away with no chance of escape.

He gave them nothing.

And if they weren't working for Bishop, then the corpse I came to retrieve isn't here. Instead they have the body of my brother – the one that I delivered to them…

What happened back in the lair?

What happened?

Fear settles into my gut, sending a cold chill around my body and through my numb and paralysed limbs.

I get the feeling I've made a terrible mistake – and there's nothing I can do to put it right.