In early February, with the longer days of the official British Summer Time still weeks away, the temperature was still dropping below freezing when night fell on Glasgow. Nobody hung around in the streets. They headed home to supper and central heating or they headed for the pubs, clubs and restaurants.

At least, the ones with homes to go to did that, and the ones with money in their pockets to spend in the bright, warm, neon lit night-time places.

Like any city there were people who lived in the shadows, excluded from the warmth and light of the pubs and clubs, the restaurants and fast food outlets.

The homeless, the desperate, the lost souls of Glasgow, walked in the shadows beyond the neon and tried to keep warm, tried to stay alive as the temperature dropped.

But something else walked in the dark shadows with them – something that had never walked in the light.

Doctor Owen Harper grumbled about the cold and pulled the collar of his overcoat up around his neck as he ducked under the police tape and approached the scene of the crime – if indeed there was a crime involved here. A tramp was frozen to death in the night. What was so strange about that in Scotland in February ?

What had made the police call out Torchwood? If it turned out that they just couldn’t be bothered with the poor bloody wretch he would give them a piece of his mind. Torchwood wasn’t there to pick up the cases the ordinary authorities had no time for.

“See what you think, Sonny Jim,” said the scene of crime officer to him as he approached the group of police and paramedics gathered near one of the reinforced concrete stanchions under the Anderston Quay flyover. He noted that it felt even colder there where the sun probably didn’t even shine in mid-summer.

The traffic either side of the central reservation moved slowly past the scene but the rubber-neckers were disappointed. The body had been covered by a forensic tent. The flap was opened unceremoniously to admit the Torchwood medic.

He glanced incuriously at the deceased at first. The tramp was dressed in second hand clothes of an indeterminate mud-brown-grey colour and broken, down at heel shoes with no laces. There was a three litre plastic bottle beside him. It was half full of the sort of white cider that could strip gloss paint off old wood.

Owen had seen the type before. Before Torchwood, when he worked in A&E, he had treated them for all sorts of ailments, from tuberculosis to gangrene, to one particularly unpleasant case with a beer bottle rammed up his backside. There was a smell that went with them all, old or young – a mixture of cheap alcohol, cheap tobacco, vomit, old sweat, urine and excrement.

The lack of that smell was the first thing he noticed in this case. Of course there was a ‘fresh’ breeze blowing under the flyover, but when he got close, especially in the confines of the tent he expected to be gagging on the odour of destitution.

There was no smell. He was too relieved not to have to conduct his preliminary examination while holding his breath to worry about that, though.

The next thing he noticed was that the man was awake when he died. Most tramps who died in the night did so while asleep. If they were awake and knew they were getting dangerously cold they tended to move around out of self-preservation.

But this man had his eyes wide open and his mouth forming a shout of surprise or shock. His hand was extended in front of him as if shielding his eyes from something painfully bright. Indeed, his frozen arm sticking up had been what drew a passing motorist’s attention and led to the 999 call.

He looked as if he had been frozen instantly, his body falling like a felled tree after death.

“HOW cold did it get last night?” he asked, though it was a rhetorical question and he didn’t expect an answer.

“Minus three,” somebody answered him. He looked around at a slim woman with a warm woollen coat and fur-topped boots and one of those hat-scarf combinations he thought might be called a snood. “I was watching the digital display on the garage opposite the shelter.”

“The shelter?” Owen queried.

“I’m Margaret Lipton,” she said. “I run the overnight refuge on McAlpine Street. The police asked me to come and see if… if I could put a name to the victim.”

“Can you?” Owen asked, recalling that the former scout hut on McAlpine Street was less than a quarter mile from the scene. Couldn’t the victim have gone there for the night instead of succumbing to the elements?

“Aberdeen Angus,” she said. “That’s the name he’s known by. I am pretty sure he comes from Aberdeen, but his surname….” She gave a slight shrug of the shoulders. “Very few of them have one of those. I said it was pointless to expect a full identification. All I can do is confirm he’s one of our regular customers… or he was.”

“Yeah, I guess,” Owen responded.

“We were chock full last night. The beds were taken before ten o’clock. We had fifteen men sitting up on the chairs in the soup hall. But if he’d come to us we’d have found a space somewhere. We wouldn’t have turned him away. At the least we’d have given him a hot meal and tried to find him a coat.”

Owen didn’t know how to respond. She looked like a nice, clean woman. She had an educated accent. What made somebody like her care about the homeless, drink-sodden, stinking Human refuse of Glasgow was beyond him. But she clearly did. The sight of the frozen corpse brought tears to her eyes and a choke in her voice.

He turned back to his preliminary examination. He touched the sunken cheek of the malnourished man and was surprised just how firm it was. The flesh was frozen solid.

“Three below….” He murmured. Of course, water froze at zero, and the Human body was eighty percent water. But a living, breathing body maintained its internal heat until much colder than that. A dead body lost heat at a known and regular rate that could be used to estimate time of death.

But even in the refrigerated units in the morgue they were less cold than this.

Even meat in a deep freeze didn’t get that solid until around minus eighteen degrees. The labels on the packets at the frozen food store warned against storage at less than that temperature.

He pressed a digital thermometer against the flesh. It registered an external temperature of minus twenty-two – colder than a domestic deep freeze.

Miss Lipton had stepped back to the police cordon and was giving as much information as she had about Aberdeen Angus to an officer. There was nobody watching when he pulled a gadget from his equipment box that Toshiko had built from some alien tech sent up from the Torchwood London archive. It was an internal thermometer that didn’t need inserting into any orifice.

It told him that the temperature of the liver was minus thirty.

He looked at the bottle of cider. Off the top of his head he wasn’t sure about the freezing point of cheap alcohol, but he doubted it was much lower than zero.

He shook the bottle. The cider frothed and fizzed. It was cold but far from frozen. Whatever caused the temperature drop in Aberdeen Angus’s body, it was very localised.

He whistled and waved to the paramedics who were on standby. When they approached with a trolley he told them they were taking the body to Torchwood.

This was in his remit.

With the body on its way to his nicely ambient autopsy room, Owen packed his equipment in the case and headed back to his car. He was closing the boot when Miss Lipton cornered him.

“Where are you taking the body?” she asked in a tone that would brook no evasion. “What’s Torchwood? I heard the police say the ambulance was going to Torchwood. Is that where you’re from?”

“It’s classified,” Owen answered. “I can’t give you any more information.”

“Classified? A dead homeless man is classified? What kind of idiot do you think I am? You’re taking his body to some private institute to do experiments on him, aren’t you? The customers at the shelter talk about that sort of thing, but I didn’t believe it until I saw this… and you. You’re not police, you’re not a doctor….”

“Actually, I very definitely AM a Doctor,” Owen said when she ran out of words. “Doctor Owen Harper, and I don’t intend to do anything to the body except find out the cause of death… because I don’t think it is as obvious as it looks and it is in everyone’s interests to know the truth.”

“Including his relatives if I can find them,” Miss Lipton argued.

“Yes,” Owen agreed. “Look, if you can find out anything about him that my organisation can’t….” He paused. Handing out business cards wasn’t something Torchwood personnel did as a rule, but he had a bundle of them in his wallet, plain white ones with a single phone number printed on them. He gave one to Miss Lipton, now. “If there is anything you can tell me….”

“You’d better be telling me the truth,” she said, slightly mollified. “Just because these people are homeless and nameless, doesn’t mean they don’t matter.”

“Of course, they matter,” Owen assured her. It was a bare-faced lie. He had never given a damn about the homeless. He generally regarded them as a public nuisance and complained about them begging in the streets, but he found himself feeling just a little ashamed of that in front of this determined woman who made it her life’s work to care for them.

The contact number mollified her, anyway. She let him get in his car and drive away.

It was barely a mile back to the Hub near Glasgow Central station. It took slightly longer than Owen would have liked because of traffic jams – probably caused by the police operation under the flyover. He had forgotten to bring the alien gadget that turned lights in his favour. Slowed to a crawl along the section of the A804 called the Broomielaw he noticed a tramp shuffling along the pavement with an old shopping trolley full of junk. He had seen the same character around the streets from time to time. He had never really looked at his face. He did, now, and was surprised, even a little shocked, to realise that the shopping trolley man was only a few years older than himself.

What turned somebody into that? Well, the economic downturn didn’t help, he supposed. But surely there was more to it than that? Even unemployment didn’t drive a man to drop out of society altogether and wander around in an old trenchcoat muttering to himself and occasionally swearing at innocent passers-by.

Miss Lipton probably knew who he was, probably knew his name and why he chose that weird, precarious life. Miss Lipton cared. Owen’s interest didn’t go beyond idle curiosity. He didn’t have the time or the inclination to find out anything more.

Besides, he had enough to do with Aberdeen Angus’s corpse.

He reached the Hub and grabbed a hot mug of coffee before heading to the mortuary. He was surprised to see that Dougal was assisting Darius in the preparation of the body for autopsy. He was wearing the sort of insulated gloves used for examining bodies in the cryogenic store. Darius was, too, which was odd. He didn’t usually worry about cold or heat.

“I like skin on my fingers,” the Torchwood Vampire-in-residence said. “This man is so cold I nearly stuck to him.”

Dougal was carefully pulling layers of frozen newspaper away from the torso with tweezers. Owen wondered what they were for.

“Insulation,” Dougal explained. “It’s a way of staying alive in cold weather on the streets. Didn’t help this poor soul, though.”

“I didn’t know you were so familiar with the streets,” Owen replied.

“When I was officially ‘dead’ I slept rough quite a lot of the time. I kept warm in doorways and ate at the soup kitchens. I got to know a lot of the homeless people. You know, far too many of them are service veterans who had problems in civilian life – depression, unemployment, substance abuse, isolation from family. The government ought to be doing a lot more for them than they do.”

Owen murmured an apology that felt completely inadequate. He had forgotten Dougal’s past life before he came to Torchwood.

“I walk in the night, too,” Darius pointed out. “I see plenty of these unfortunates. There is a sort of unwritten rule among my own kind – we don’t feed off them. They can’t spare the blood.”

“Small mercies,” Owen said as he used his alien-tech thermometer again and wasn’t sure whether to be surprised or not when he found that the external and internal temperatures of the body were exactly the same. Even in the body bag in the ambulance and in the relatively warm mortuary there had been no thawing.

“He didn’t die of hypothermia,” Dougal pointed out.

“You’re a medic, as well?” Owen commented.

“I’ve died that way a couple of times,” Dougal continued, again pricking Owen’s conscience with a reminder of when life – and death - had been tough for him. “It’s a gentle way to die, really. You become gradually insensitive to anything – you even feel warm in a strange way – and you just fall asleep. Angus died very suddenly as if something reached in and froze his heart in an instant.”

Owen was tempted to say something sarcastic in response to such a poetic description of sudden death, but he didn’t, mainly because he thought Dougal had summed up his own initial diagnosis succinctly.

“Nothing natural to this world can do that,” Darius said.

“What about anything unnatural?” Owen asked him. “Are there any ghoulie types that feed on Human body heat?”

“There is a northern European vampiric creature called a ‘Welur’,” Darius answered, pronouncing the ‘W’ more like a ‘V’. “They appear as beautiful, seductive women with a cold, deadly kiss.”

Everyone looked at the body of Aberdeen Angus. It was perfectly possible that an old man of at least sixty might be taken in by such a creature but they all felt that a beautiful, seductive woman, even one with murderous intent, might choose a rather more attractive victim.

“There’s a Scandinavian legend of Jack Frost,” Darius added. “But he is a mischievous figure that heralds winter cold. He only kills when angered. I don’t know how somebody like Angus could have angered him.”

“Then we have something alien going on,” Owen concluded. “An alien that kills with sudden extreme cold. That means there’s no point in looking for a motive. Murderous aliens generally don’t care. Humans are just meat, or some mineral, some part of their lifeforce, that the bloody alien wants. What we need to find out is where the bastard is. I’ll get Toshiko to run a trace for alien energy. If we’re lucky this thing leaves a trail we can pick up a mile away.”

It was a small hope, but Toshiko set about scanning the city for ‘unusual’ traces. It didn’t help that they couldn’t say what sort of ‘unusual’ they were looking for.

“The best I can do is a sharp localised drop in temperature about half past five,” she said. “It only lasted a few minutes, but it was in the area where the body was found. I think you could put that down as the time of death.”

“That’s a start,” Owen conceded. “Is there any way you can set up an alarm of some sort – for any future temperature drops of that sort.”

“I can try,” Toshiko promised. “But it’s going to be like shutting the door after the horse has bolted. Even if we get a trace… won’t we just be able to find the body faster. We can’t save anyone.”

“Try,” Owen urged her.

“There’s something else,” Toshiko added. “I’ve identified Aberdeen Angus.” She held up a Torchwood evidence bag containing a very bedraggled looking old age pension book. It had traces of newsprint on the defrosted paper cover. “His real name was Angus McClew. He was seventy-two years old and he left his comfortable home in Aberdeen not long after his wife died four years ago, cutting himself off from his old life completely.”

“It looks like he’s been cashing his pension regularly,” Owen said, noting the post-office stamps on the stubs in the book. They went right up to Monday last week. “And spending most of it on drink I suppose, instead of getting himself a warm place to sleep and a change of clothes.”

“He has a daughter living in Greenock,” Toshiko added. “It’s only a fifty minute drive. I was thinking of going at lunchtime with Munroe… to inform her that her father is dead.”

“That’s not exactly our job,” Owen pointed out. “Not unless there’s anything the relatives could tell us about the deceased. In this case, I hardly think….”

“I know it’s not our job,” Toshiko said. “But I think it’s our duty. Munroe said… he felt like dropping out of everything after his wife died. He thinks he knows what the old man was going through.”

“Yeah…” Owen felt his own memories suddenly pricked. He had gone through a period of utter devastation when he lost Katie. If Torchwood hadn’t given him a new reason to exist he might have wound up the same.

He might have been the shopping trolley man after all.

“Ok,” he conceded. “On your way, go and see Miss Lipton at the McAlpine Street Shelter. I think she’d like to know we’re doing… our duty.”

He was definitely going soft, Owen admitted to himself. Time was he’d have just finished up the autopsy and then arranged for the usual funeral firm to do a cremation. These days, Torchwood was a caring institution.

In the mortuary, Dougal and Darius between them had finally removed the multiple layers of unwashed clothing and old newspaper and washed the body of Angus McClew. They had combed through his hair and beard looking for anything relevant to the case – or perhaps just making him look more like the man he used to be before he decided to be nobody.

But he was still frozen solid. The body temperature had only risen by a degree.

“I don’t think there is any point in an autopsy even if I could do one,” Owen decided. “Make him decent and put him into a drawer. Don’t bother refrigerating it. I don’t think he’ll need it.”

There really didn’t seem to be anything else to do. It was far from a conclusion to the case. He still didn’t know what had caused the old man’s death – except that he knew it wasn’t anything that belonged on this planet. He didn’t know if it would strike again. He didn’t know if it was only interested in down-and-outs or if it would start targeting members of the public.

He found himself correcting that view. The down-and-outs were members of the public, too. They mattered. Nobody gave some bloody alien permission to turn them into icicles. They weren’t expendable, they weren’t surplus humanity to be given up without a fight.

But he didn’t have a fight until he had more evidence of who or what had done this, and there was nowhere to find the evidence.

“Dougal,” he said. “How do you feel about searching the area around the flyover for physical evidence?”

“I don’t feel particularly thrilled about it, boss, especially in this weather, but orders are orders.”

“Good. I’ll come with you.”

They walked back towards the place where Angus died. They did so dressed in old coats and formless woolly hats that covered their tidy haircuts and good clothes. By the time they had been out in the cold air for a few minutes their faces were raw enough to pass for homeless at a glance. Owen couldn’t help noticing that people in the streets looked at them differently – or rather didn’t look at them at all.

The police operation was over now and traffic was flowing both ways underneath and on top of the flyover. Unnoticed by anyone at all they slipped through a broken section of fence and picked their way across the rough ground that would have been a brand new block of offices by now if the Credit Crunch hadn’t halted the project. They were technically trespassing, but they had begun to feel pretty much invisible to the ordinary people of Glasgow and didn’t really care about such details.

They were visible to the homeless people, instead. When they drew close to a group of them hanging around a rough campfire they were offered a space within the range of its warmth.

“You’re new around here, aren’t you?” said one of the men. “You’ve come in from the country?”

“Something like that,” Dougal responded. “Is there any work going around here?”

“Not a chance,” he was told. “Best you can do is go down to the social.”

“Can’t,” Dougal said. “I don’t have any ID.” That had been his problem when he was ‘dead’. He had become a non-person with no safety net of any kind to support him.

“You can get some food at the shelter. There’s a woman there who’ll see you right. But the nights are bad this time of year. A bloke died last night just down that way.”

“Yeah, we heard,” Owen commented. “Was he old?”

The men shrugged. “Old enough.” There was nothing unusual about dying of cold in February. It happened. They weren’t especially upset, not because they lacked sympathy with the dead man, but more, perhaps, because they were glad it wasn’t them lying on the slab.

They had seen nothing strange, and it was obvious that these men would recognise unusual if they saw it. Unlike ordinary people, they noticed everything that was going on around them. Noticing things was what they did. What else was there?

Owen felt his mobile phone vibrate in his pocket. He had put it on silent because it didn’t quite go with the impression of a homeless, jobless wayfarer. He made an excuse to leave the warmth of the fire and checked the text message as soon as he was far enough away.

“Come on,” he called to Dougal. “Toshiko’s cold detector picked up a signal not far from here. Darius sent the co-ordinates.”

Dougal ran after him and soon outstripped him as they headed across the building site and vaulted over the sagging chain link fence into Washington Street. The gentrification of Glasgow hadn’t even reached this street before the Credit Crunch came down. It was still a dark defile between Victorian red brick mills now converted into small business units.

The co-ordinate on Owen’s iPhone was a derelict space where one of the old buildings had long since been demolished and was waiting forvsomebody to buy it for ‘mixed use development’ as the battered estate agent sign suggested. It was covered in rough grass and weeds. They picked their way towards a supermarket trolley lying on its side, the ragged contents strewn around a body that looked almost like a pile of rags itself.

“It’s the trolley man!” Owen exclaimed, between gasping for breath. Dougal recovered from the run faster than he did and bent to examine the body.

“Frozen solid,” he confirmed.

“Shit!” Owen swore. Then he swore again when the iPhone indicated a new message from Darius and a new co-ordinate, no more than about a hundred metres from where they were standing.

At the same time, another phone rang. He pulled the cheap, pay-as-you-go receiver from his pocket. The SIM card in it corresponded to the number on his business cards. If he gave the number to somebody who became a nuisance, he could easily toss it in the recycling bin and get a new one.

This wasn’t a nuisance call. It was Margaret Lipton of the McAlpine Street Shelter, and she was crying.

“They’re dead!” she told him. “All of them. They’re dead.”

“We’re coming,” Owen assured her. “Right now.”

Dougal was already sprinting across the derelict ground. McAlpine Street was parallel with Washington Street and the old scout hut was the only old building left among the new office blocks.

Owen was lagging behind. By the time he crashed through the front entrance Dougal was comforting Miss Lipton who clung to him as if she didn’t care that he preferred the company of men.

Owen left her to it and examined the bodies of the half dozen men sitting in a ‘social’ corner where newspapers, old paperback books and draughts boards were available for those customers of the shelter and soup kitchen who wanted to spend a quiet hour or so out of the cold.

Except the cold had come to them. Each one of them was dead. It had happened instantly. One man was still holding a mug of tea to his lips. The liquid in the mug was still warm, but the man was deep frozen.

He straightened up from examining another victim and noticed a shadow moving in the corner of the room – exactly as shadows weren’t supposed to move independently of a real body to create one. It had a vaguely Human form, and even a certain depth, and Owen had a stray thought about Peter Pan’s missing shadow that he pushed right back down again. This was a murderous alien not a playmate.

“Stay right there!” he called out. “Don’t even think about freezing anyone else.”

It was possibly the most idiotic thing he had ever said. He braced himself to die quickly as the shadow bore down on him.

Then Dougal was there, pushing him out of the way, screaming as the shadow melded with his body. Unlike the others, he didn’t freeze to death instantly. His face was pale and his mouth twisted in shock, but he fought the alien inhabiting his body.

“Kitchen!” he screamed, stumbling across the hall and shouldering open the door to the warm, steamy room where Miss Lipton and a team of volunteers cooked meals for the homeless. The double ovens of the wide commercial standard cooker were already hot.

Owen held Miss Lipton back at the door, guessing just what Dougal meant to do. He watched him douse himself with a catering can of cooking oil and then open the oven door and thrust his arm in. His sleeve caught fire straight away and the flames spread easily. He ran for the fire exit from the kitchen, out onto the street. He managed to reach the derelict land before his engulfed body collapsed.

Owen ordered all of the bodies to be taken to Torchwood. The dead homeless men were attended to by Darius. He looked after Dougal. In the rest area Toshiko comforted Miss Lipton and tried to explain why her clients had been targeted.

“Come with me,” Owen said to her after two long, difficult hours. “I need to show you something.”

He brought her to the mortuary where all of the dead men had been cleaned, hair and beards tidied and their bodies covered with white sheets.

“We’ve positively identified all but one of them,” he said. “The police are informing the next of kin where there is one. Later, the bodies will be transferred to an undertakers we have a contract with. They’ll be given proper coffins. They’ll be buried with all the dignity and decency they deserve.”

“What about the ones with no relatives, or where the relatives don’t want to know?” Miss Lipton asked. “That’s why a lot of them turned to the streets in the first place.”

“Torchwood will foot the bill,” Owen promised. “It’ll be done right.”

“Thank you,” she said. “Especially… you lost your friend so… so terribly.”

“That’s another thing,” Owen told her. “Dougal is really hard to kill. Come this way, now.”

He brought her to the recovery room. Dougal was lying under a sheet, too, but his head was on a soft pillow and his eyes were open. The flesh that his nano-genes had replaced still looked a little red, but it was whole. Owen didn’t bother to explain to Miss Lipton how painful it was repairing one hundred per cent first degree burns. Dougal didn’t, either.

“I’m a sort of miracle,” he told her. “It’s best not to question how or why. But I need to tell you…. The alien… I felt its mind when it took me over. It came to this planet because of its warmth… its organic warmth. It craved it… fed off it. But it knew it couldn’t take people at random. It knew there would be a backlash. It… took the homeless… because it identified them as surplus, as Human refuse… that nobody would miss.”

Miss Lipton expressed her outrage at that loudly. Bad enough that other humans held those opinions. Now an alien had decided that the people she worked to look after were accounted expendable.

“I agree,” Dougal told her. “That’s why I knew it had to be destroyed. If there had been an ounce of mercy in its thoughts…. But it just wanted to devour Human warmth.”

Owen nodded. He was new to such altruistic views, but he wasn’t going to let an alien decide who was surplus to the Human race, either.

“Toshiko will take you home now,” he added.

“No, I need to go back to the shelter. I need to organise the evening meals. There are plenty more hungry people out there. I’ve got to carry on the work.”

“Toshiko will take you there, then,” Owen assured her.

“That’s the truth,” Dougal said as she left them. “We’ve all got to carry on the work. Torchwood’s work is never done.”

“You can have a couple more hours’ sick leave before you carry on,” Owen told him. “Then back to business.”

“Yes, boss,” Dougal said.