Less than half a mile from the office block stood the first few buildings of a modern university campus. Separated from the rest of town by the six-lane ring road that ran along the front of a large and recently built accommodation block, the university grounds were vast. The medical school located at the far end of the complex formed part of one of the city's main hospitals. With specialist dental, children's, skin and burns departments, the hospital itself had been fundamental to the continuing health of the city's population. Tonight only one doctor remained on duty. Tonight there was only one doctor left alive. The modern accommodation block had individual rooms for several hundred students.

During the days since the disaster somewhere in the region of fifty survivors had gathered there. Some had been near the hospital or university when it had happened, others had found their way there by chance, a few dull lights and occasional signs of movement revealing the survivor's presence to the otherwise empty world. Dr Phil Croft, the last remaining medic, had just started his morning rounds when it had begun on Tuesday morning. He'd helplessly watched an entire ward full of people around him die. He had just discharged a young boy called Ashley with a clean bill of health after an appendectomy two weeks earlier. Seconds after finishing his examination of the boy the helpless child had fallen at the doctor's feet and was dead. And it hadn't just been the children. The nurses, parents, cleaners, helpers, his fellow doctors and consultants too - everyone else on the ward had been struck down and killed within minutes. But even now, now that the population had reduced from millions to, it seemed, less than hundreds, Croft was still on duty.

It was something that came naturally to him, an instinctive, inbuilt response. One of the survivors needed medical attention and he felt duty bound to provide it. He walked slowly through the quiet building towards the room where the woman who needed him lay. The corridor he moved along was dark and shadowy and was lined with doors leading to individual student rooms on either side. Using his torch to guide his way he glanced into a couple of the rooms as he passed them, the unexpected light causing mild panic amongst the survivors cowering in the darkness. There may have been more than thirty or forty people sheltering in the building, but many of them were sheltering alone.

Apart from a handful of people who had begun to group together, the majority of survivors chose to remain in frightened isolation, too afraid to move or to speak. The doctor found the room where the woman was resting. She was very attractive - tall, well-toned, strong and nine months pregnant with her first child. Croft was strangely drawn to Sonya Farley. His girlfriend - Natasha Rogers, a nurse in one of the burns units - was dead. In those painful first few minutes on Tuesday morning he had run from his building across to Tash's unit and had found her cold and lifeless on the ground with the rest of them, dead like everyone else.

She had been eight weeks pregnant. They hadn't had chance to tell anyone about the baby, not even their parents. They'd only just got over the shock of the unexpected pregnancy themselves. Now Croft found that focussing his efforts and attention on Sonya helped his constant, gnawing pain to ease slightly. It somehow made it easier for him to cope with his loss, knowing that he would still be able to help Sonya to bring her baby into what remained of the battered world. And Christ alone knew that Sonya deserved help. When the disease had struck she'd been sitting in the middle of an eight mile traffic jam on the main motorway leading into town. She'd walked through more than four miles of unremitting horror and devastation to reach the hospital. Satisfied that she was well and leaving her sleeping soundly, Croft made his way downstairs. He entered a large rectangular assembly hall where a few survivors had gathered together. He found the lack of any noise or conversation more difficult to handle than the solitude and he kept moving, crossing the room diagonally and leaving by another exit. The fact that everyone had become so painfully withdrawn somehow made the situation harder for him to deal with but, then again, what was there to talk about?

Did any of the survivors have anything in common? Even if they did, chances were that whatever interests they may have once shared were gone now. What was the point of talking to anyone else about your taste in food, clothes, film, music, books or anything anymore? And as every survivor who did speak quickly found to their cost, it didn't matter who you tried to talk to or what you talked about, every single conversation inevitably began and ended with pointless conjecture about what had happened to the rest of the dead world. Croft needed nicotine. He walked the length of another corridor then turned right and sat on a step halfway down a short staircase which led to a glass-fronted entrance door. This small, secluded area had become something of a smoker's corner and two other survivors - Sunita, a student who lived in the building they were sheltering in and Yvonne, a legal secretary from a firm of solicitors on the other side of the ring road - were already stood there, smoking their cigarettes and staring out into the darkness. Croft had successfully kicked the habit five months ago but had started again yesterday. It didn't seem to matter anymore. He lit his cigarette and acknowledged the two women who turned around to see who it was who had joined them. `You all right Dr Croft?' Yvonne asked.

He nodded and blew a cloud of smoke out into the still air just in front of his face. `I'm okay,' he replied, his voice quiet and tired. `You two?' Sunita nodded instinctively but otherwise didn't reply. `My Jim,' Yvonne said softly, `he used to love the dark. Sometimes, when he couldn't sleep, he'd get up and go and sit in the bay window at the back of the house and watch the sun come up. He used to love it when the birds started singing. If he was feeling romantic he'd wake me up and take me downstairs with him. Didn't happen often, mind.'

Yvonne smiled momentarily and then looked down at the ground as the sound of bird song in her memory was swallowed up and overtaken by the all consuming silence again, leaving her feeling empty, vulnerable and lost. She wiped a tear from her eye. She was in her early fifties but the strain of the last few days had left her looking much older. Her usually impeccable hairstyle was frayed and untidy, her once smart business suit now crumpled and unkempt. Sunita sensed her grief and put a hand on her shoulder and pulled her close. She knew that Yvonne's husband had worked in an office across town and that, on the first morning, she'd gone there and found him dead at his desk, face down in a pile of papers. `I can handle the dark as long as I'm not on my own,' Sunita said. `When I'm on my own my mind starts to play tricks. I start convincing myself that there's someone else there.' `You'd be lucky to find anyone these days,' the doctor sighed. `Anyway, never mind the dark, I'm having enough trouble trying to deal with what's happening in the light,' he admitted. `You any closer to working out what's happened yet?' Yvonne asked innocently as she turned to look out of the window again. Croft shook his head and looked away, trying to hide his sudden frustration and annoyance. Why did everyone assume that just because he was a doctor he'd somehow be able to find a reason and explanation for their impossible situation? Christ, no-one had ever come across anything like the virus or disease or whatever it was that had killed so many people in such a short period of time. And to his knowledge no-one had ever risen after two days without moving or breathing either.

Nothing had ever happened like this before so of course he didn't know what the bloody hell had caused it. With his sudden anger close to boiling to the surface he forced himself to bite his tongue and remain calm. Inside he felt like screaming at Yvonne and telling her to go and look for the answers to her questions in a fucking medical encyclopaedia but he knew it wouldn't achieve anything other than to make an already unbearable situation more tense and unbearable still. He took a deep breath and sucked in another lungful of smoke. She wasn't trying to wind him up. He silently reminded himself that she was just trying to get through this like everyone else. `You checked on Sonya?' Sunita asked. He nodded. `She all right?' `She's fine. She's sleeping.' `Lucky cow,' mumbled Yvonne. `I haven't slept properly for days.'

Croft finished his cigarette and dropped the glowing stub onto the floor before putting it out with his foot. He held his head in his hands. Without power it was as dark inside the building as the night was outside. The brightest lights were the glowing ends of Sunita and Yvonne's cigarettes moving through the cold air. Exhausted, the doctor closed his eyes and tried to clear his mind. He'd tried several times in the last few hours to completely empty his head of all conscious thought and switch off but nothing seemed to work. Even the smallest, most insignificant noise or the slightest thought was enough to bring him crashing back to reality in seconds. And even though he was one of only a handful of people left alive, the disturbances and distractions were constant and unending. `You see that young lad who came in this morning?' Yvonne asked Sunita. `Poor little bugger. Could only have been six or seven years old. One of the others spotted him running down the ring road. Said his mum had died and he'd come into town to try and find his dad. Wouldn't be told that he was probably dead too...' `How are we supposed to explain this to the children?' Sunita sighed. `If we can't make sense of what's happening, how are we supposed to make them understand?'

`Depends how old they are,' Croft said, lifting his head and looking up again. `Why?' `Because kids of a certain age will accept anything you tell them,' he explained. `I envy some of them. A two year old will grow up thinking this is how it's always been, won't they? Bloody hell, imagine how much easier the last few days would have been if you hadn't had to spend hours and hours trying to work everything out? If we'd had someone who could have told us what had happened and why, even if they weren't right, we could have just got on with sorting out the mess instead of trying to reason it out and explain it to ourselves.' `But those poor kids,' Yvonne continued. `Imagine losing your parents and being on your own like that.' `We've probably all lost our parents,' Sunita mumbled. `I know, but...

' Yvonne's words were interrupted by the noise of a body suddenly crashing into the glass double-doors directly in front of her. Nervously she stumbled back and tripped. Croft jumped to his feet and steadied her. Strangely curious he took a couple of slow, cautious steps closer to the corpse. Its gaunt face was pressed hard against the cold glass and it moved slowly along from left to right, leaving behind it a long smear of grease and a trail of bloody, germ-filled saliva. When it reached the end of the glass it clumsily turned around and began moving back in the opposite direction. `What the hell is going on here?' Croft asked under his breath. `What's the matter?' Sunita asked. She stared at the creature, her face screwed up with disgust. It didn't look any different to any of the thousands of other diseased bodies she'd seen. `I don't like this,' the doctor admitted.

He moved closer still and studied the figure's staccato movements. `This one isn't like the others.' `Why?' Sunita whispered. `Because it isn't going away.' `What?' `Look at it. By now it should have turned around and wandered off into the night again. It's staying here for a reason. It's almost as if it knows that we're in here.' `Like hell...' `Give me another explanation then? I tell you, this body is watching us.' As if to prove his point, he moved still closer towards the glass until his face was just inches away from that of the cadaver. He then moved across to his right and then, slowly and with painful lethargy, the body did the same. He moved back and, after a few seconds delay as it shuffled itself around, the corpse followed.

Yvonne was scared. She found it almost impossible to bring herself to look at the diseased shell which had, less than a week ago, been a perfectly fit and well human being. She had crept halfway up the staircase and was peering down through the railings like a frightened child. `So what does it mean?' she asked from a cautious distance. `One of two things,' Croft replied, not taking his eyes off the body. `Either this one has somehow been less affected than the others...' `Or?' Sunita pressed anxiously. `Or they're changing.'