'You did what?' I demanded.

'We just sort of took it,' he replied. 'It's some kind of mutant. It bit Tom, he's really sick!'

'Where is he now?' I pulled my phone out my pocket, I had Nick on speed dial but in all honestly his lab wasn't all that far from here and I knew it wouldn't take too much longer to reach him in person. So I set off. Duncan followed after me.

'I don't know. You're not calling the police, are you?'

'Honestly, the police would be better.' I threw open the medical block doors, storming out to cross the pond and head towards the palaeontology building. The sound of the line connecting beeped through my phone, 'Nick?'

'Yep, hello,' he returned, 'I was just about to set off to your lab, but I realised you probably aren't in the physics block, are you in medical?'

'I'm coming to find you,' I said, 'we've got a huge problem.'

'I'm really sorry,' Duncan moaned. I side-eyed him.

'Duncan, call Connor.' Then back into the phone I directed, 'I'll meet you at the car Nick.'

It was chorus of doors slamming up and down the street as we all jumped out the vehicles and crossed the road towards Tom and Duncan's flat.

'How infectious is this?' Ryan yelled from the doorway as we stepped up onto the pavement.

'This thing isn't a virus,' I called back, 'it's a parasite and Tom's the host. We have to isolate him before he can pass it onto anyone else. Whatever you do when you go in there, don't let him come anywhere near you.' Ryan nodded. He sent his men into the flat first before he followed.

'And this is the last place anyone saw him?' Nick questioned as he stepped over the threshold into the hallway of the house.

'Yeah,' I responded, 'but that was an hour ago, the chances of him still being here are slim.'

'How long has he got?' When I didn't respond, Nick turned back to look at me and read the expression on my face. 'Oh, Anna...'

I shrugged. 'If he's here... Maybe...'

'Tom? Tom? Where are you mate?'

I held Nicks gaze a little longer before I tore my eyes away and forced myself to perk up.

The lounge was just as messy as the last time we'd been here. It must have been a few months since Connor and I had come over. We used to hang out all the time, the five of us. Connor started referring to us as "the Hitchhikers," and gave us all nicknames. The flat had been our Heart of Gold. It had become more of a home to us than the house on the hill after the accident. Recently, neither of us had managed to come over anywhere near as often as usual, and nowhere near as much as we'd have liked.

Soldiers came turning back from the rooms, shaking their heads, looking hopefully at one another like each one of them was hoping someone else had found him.

My stomach twisted again. 'Where is he?' I asked. I looked to Ryan. With a final shake of his head in denial, I swore under my breath.

'Which one is his bedroom?' Nick asked.

'This way.' I lead him down the hallway to the bedrooms, where, as we pushed the door open, we found Stephen crouched there on the ground in front of the bed. 'You know those movies when you think the killers finally dead and then all of a sudden they just jump up again.'

'Yeah,' Ryan agreed, appearing behind us and startling me, 'I hate those films.'

'Me too,' Stephen said. I crouched down beside him and saw his head turn towards me through my peripherals. 'After you.'

I slowly turned my own head to meet his gaze. Then, looking back to the dodo, I dropped my knees to the carpet and crawled towards it. I lifted my hand above its head.

Then I hit it.

There was nothing.

'It's dead,' I said.

'Are you sure?' Nick asked.

'Pretty sure. Trust me, I'm a doctor. Don't tell anyone I just smacked it like that; that's not how you're supposed to check anything's vitals. .' Then, after hitting it a second time just to be safe, I sat back on my heels. 'Alright.' I stood up, lifting the bed from the floor and standing it on its side. 'Bag it up, but be careful!'

But something caught my eye in the piles of mess beneath Tom's bed. My face dropped of its own accord in utter confusion.

I had never been expecting to see women's underwear under there. On any other occasion I probably wouldn't have noticed it, but it was so out of place it had gravity- like the sheer concept of it was enough for me to consider if I had somehow entered a parallel reality.

It wasn't like the underwear was hidden either; it was strewn atop a couple of pairs of boxer shorts.

Connor must have read my expression because he stopped beside me and followed my gaze down to the bra and matching pair of pants.

He blinked a few times in confusion, then suddenly lifted his head and looked at me wide eyed. His mouth fell open. 'Is that your underwear?' he said without thinking. Suddenly, everyone was interesting in where I was pointing, and unabashedly Stephen took a step forward to peer down into the pile. Meanwhile Connor was gawping, trying to speak, so genuinely shocked like he already believed it was mine. 'Have– have you and Tom been...' He trailed off. I knew where he was going.

'No I haven't been fucking Tom,' I returned.

'Then what's it doing here?' Connor asked in outrage.

'Obviously it's not mine!'

Duncan choked. It was far too suspicious. I turned my head to where he was standing in the doorway.

All it took was a look. 'I saw him steal it from your drawer!' he blurted.

'What?'

So it was my underwear? That explained why it looked a little familiar. 'It was like three summers ago when we were all living in the house with you and–'

'Why didn't you stop him?'

'He... made some good points.'

It was my turn to be outraged. 'Excuse me?'

'It looked really soft.'

I'd been betrayed. This was unbelievable. I brought my head back to Connor. 'Did you know about this?'

He gasped. 'Of course I didn't! I'd have caved his bloody head in if I'd had any idea he was stealing your underwear.'

Nick cleared his throat, scratching his eyebrow to try and cover his amusement. I looked at him. The amusement disappeared from his expression.

'But Anna...' Connor sighed. 'It's Tom.' I knew what he was saying: Tom hadn't meant anything by it. He had always been awkward and never had much luck with women. Girls walked all over him in sixth form, because he was way too nice and way too trusting and too gentle to stand up for himself. He was probably incredibly sexually frustrated.

I turned my attention quickly to Duncan, suddenly wondering if this was why he'd never been able to look me in the eye. 'What happened?'

'Well,' he spluttered, blushing bright red and clearing his throat, 'I imagine Tom probably used your um... panties whilst he was–'

'With the dodo!'

He cleared his throat again. 'Well, um, one minute it was friendly and the next it just went crazy.'

'The parasite changes the Dodo's behaviour,' I explained to him, 'to suit its own purposes.'

'Which were?' Ryan asked. I'd almost forgotten about all the other men in the room and I was glad that I was cross because I didn't have the energy to feel any tinges of embarrassment too.

'To reproduce,' I finished. 'That's why it bit Tom. So, it can incubate its eggs in a new host. It's not safe to be around him.'

'That's why it bit Tom?' Duncan repeated questioningly.

'Where?'

'On his wrist.'

I caught Nick's eye and shook my head. I knew he understood. I stretched out a hand and took a hold of Connor's forearm. 'I'm sorry,' Nick said. He probably knew- I didn't know how- but he knew I didn't want to be the one to say it. 'Maybe if we'd got to him straight away then he'll have stood a chance.'

Connor frowned. 'What?' his head whipped down to me. 'A? What are you saying?'

I took a deep breath. 'We're not giving up on him,' I assured him, 'but you need to know the probability of the situation and it's likely that once we find him there won't be anything we can do to stop the parasite.'

'He's...'

'Connor,' I said. 'Lets find him before he hurts anyone.' I held his gaze for a moment. Then he nodded back at me. 'The parasite is light sensitive so wherever Tom is he's going to be trying to stay in the dark,' I elaborated, pointing back up to the light bulb above my head. I was met with several confused looks in return. I cocked my head, 'don't tell me no one else had noticed that.' The silence was an answer in itself. 'Right,' I concluded.

Stephen sighed, stepping forward to pick up the dead Dodo and put it into the bag one of Ryan's men was holding out for him.

'We'll send this back to the lab,' he said.

'No,' I interposed, 'I mean, not the one at the home office, anyway, I want to take it back to uni.'

'Any reason why?'

'Well, I'm halfway through some other stuff there.' I followed the man with the bag back through the house and out the front door, the others following behind. 'Nick? Can I have a second?' And I gestured up a little way up the pavement.

Nick nodded his head and stepped away with me. 'Everything alright?'

'Honestly? I don't know. I think- I don't even want to think about it but I think that Tom...'

He lay a hand on my shoulder. 'I have to go back to the home office. They want to know how we let Helen get away,' he returned calmly in explanation. 'I'll take Connor and the other one with me; someone should probably be responsible for them in the meantime, and he'll need to be questioned.' I nodded knowingly. 'After that I'll come find you, okay?'

'Okay,' I said. 'Thank you.'

'Of course. What was the results on your blood?'

'I didn't have time to wait for it. It should be ready by the time I get back. I put it on a 45 cycle–' Then, realising he wouldn't know what that meant, I corrected myself and lowered my voice. 'I'm separating it. Antibodies appear in white blood cells called B lymphocytes, so if it was a vaccine Helen put into me that's where I'll find it a trace of it.'

'Okay. Call me when you know something.'

'You know I will.'

I went to the medical building first, since I knew once I had the bagged Dodo with me I wouldn't want to carry it in to any sterile areas and contaminate them. I put the blood in my pocket, traced the line of stitches inside my cheek with my tongue, and headed back to the car to take the Dodo with me to Cutter's lab.

Ordinarily, I'd take something like this back to the room at the home office where I had all of the equipment I needed to do a proper post-mortem, or I would head down to the hospital and ask the home office to facilitate the use of a morgue where I wouldn't be worried about somebody stumbling in on classified information, but Cutter's lab was adequately equipped, and more than that he had the right sort of microscope for looking at my blood.

I set up the dodo first. Cleaned it, laid it out on the tray and set up my tools before I finally got around to taking the blood from my pocket. Reaching for the microscope and settling on the nearest stool, I dropped a pipette into the blood mixture to squeeze some onto a slide. I put a cover slip over the top. Just as I lowered my eye to the eyepiece, my phone started to ring.

'Hello?' I put one eye to the glass and shut the other.

'It's me,' Nick called out from the other end, 'I just thought I'd let you know Tom's bitten a surgeon, he's going to need to go in for surgery, but he should be okay.'

'So you've found him? He's at the hospital?'

'No,' Nick denied, 'he was here, but he's not anymore. Look, Stephen's with Connor and Duncan now, we're trying to work out where Tom's next stop will be. He knew he was sick, so he went to the hospital, it shows there's still something in him that's thinking rationally.'

'That's hopeful.'

'There's something else you should know. According to the surgeon Tom tried to pull his trousers down.'

I sat back from the microscope. 'Oh,' I said. Then I sighed. 'Oh... No, it makes sense.'

'Huh?'

'So if Tom's been to the hospital we know the parasite doesn't completely take over it's host's mind right away. But we know it's effecting his behaviour, causing him to lash out.' I shut my eyes and rubbed my forehead. I was starting to get a headache. 'We also know this parasite's main objective is to reproduce. Combine that instinct with a sexually repressed testosterone filled guy in his 20's and he's becoming dangerous. We've got to find him; he's 6'2 and that parasite is going to make him much stronger than usual, and now he's been fought off once the chances are next time he's going to go for a much easier target. A lot of women wouldn't stand a chance.'

I heard Nick sigh from the other end. 'We're trying our best to find him.'

'I know. And you will.'

There was a noise behind me and I turned to glance over my shoulder but I couldn't see anything through the translucent vinyl curtain. I must have left the door open. A breeze ruffled the plastic. I turned back. 'How are the others?'

'Lester's blaming Helen for releasing a pandemic on us. He thinks she did this deliberately.'

'Do you?'

'I don't know what to think,' he replied, 'but I know it's never a good thing to be agreeing with Lester.'

I hummed. 'Well, there's definitely something in this blood,' I explained. 'I don't know what yet, I'm gonna have to run some more tests to see if these are antibodies or pathogens.'

Nick said okay, but I immediately assumed he didn't really know what I was taking about again and so, with another glance back around at the dodo I sighed.

'You alright?' he asked.

'Yeah, I just-'I cut myself off.

'Hey, you've had a really hard day already, if you want to go home, get some rest...'

'No, I don't need to do that, it's just...'

'Tom?'

'Yeah.'

'I'm so sorry.'

'I know. Me too. I just feel bad for Connor, you know. They've been best friends since they were sixteen and... its not fair. This could... this could be it for him. This could be the tragedy he doesn't come back from.'

'He'll be okay.'

I sighed. 'We don't know that.'

'We do,' he returned. 'Because he's got us.'

I nodded. 'Yeah. Yeah, you're right. Listen I'm gonna... I should cut up the dodo, um- I'll call if there's any developments or anything –' The noise sounded again behind me and this time I whipped my head around, slightly more paranoid about it. I got up off the stool.

'Yeah, okay, see you soon, Anna.'

'Yeah, see you soon...' I responded slowly, 'bye...' I hung up the phone, all the while leaning further round towards the edge of the curtain to the gap. Just before my eyes reached it the lights went off. I jumped, momentarily turning my attention up to lights as my heartrate spiked, before I lowered my eyes to the gap in the curtain. Except now there was someone on the other side.

'... put the phone down,' he said.

It was Tom's voice, or at least it sounded almost like Tom's voice. I took a hold of the edge of one of the sheets of plastic and pulled it aside.

My breath caught in my throat.