He stood there in the doorway of his office staring at the door that now filled a previously blank stretch of plaster and brick. The impossibility of it had him half-determined to believe the door had always been there. He walked past it and into the kitchen, set to rummaging through microwaveable food in the freezer while trying to remember what might lie on the other side. The truth of course was nothing. He lived twelve floors up and the door was in an external wall. Panic sent him back into the hall.
  There was no comfortable solution. Doors did not just appear in walls, nor did people forget those that had always existed. Accepting these two viewpoints â and how could he not? â left him with little room for negotiation.
  He took a closer look at the door. The peeling paintwork was fragile and cracked â a cream psoriasis that exposed baby-sick green flesh beneath. That also marked it as different from the others in the flat. All of the doors were cheap pine, stained dark when he and Jo had first taken over the tenancy. Flecks of varnish still marked the bedroom carpet where the plastic sheeting had come awry, just one of the many stains that haunted that room in Jo's absence. A faded brown ring from an overfull coffee mug mocked the bedside table like the after-effect of a joke shop telescope; a tapering black line stretched across the wall from where the metal bed frame had scratched the paint during the move; crisp droplets of blood sat on the rug from a nosebleed. This was a home of dirt ghosts.
  He was reluctant to touch the door but the urge to know that it was solid and real was strong. He gently brushed the surface, scattering a puff of foreign paint chips.
  Having no idea what to do, he postponed the problem by grabbing his coat and leaving the flat. Outside, the city was an alien darkness, safe paths lit by the scattered glow of grafittied lampposts and shop signs. He felt lonelier than ever. He had nobody to call on or to run to. When they had first moved here he had felt no need to make friendships; now that she was gone he found he had no idea how to. Singularity was a virus and became more debilitating with time.
  To be out and in the air was still a relief. He felt surrounded by space, despite the towering tenements and office blocks. The sound of a train rattling its way across ancient track a few streets away reminded him there was a world beyond the city... if only he could find the reason to visit it.
  Eventually, sick of directionless walking, he sat at a bus stop and smoked a cigarette.
  Time to go home.
  The door was still there but he avoided looking at it and went to bed. Perhaps sleep would steal it from the wall and he could wake to clean white plaster and the flat he knew. Despite lying awake for hours â attempting to not think about the door with such fervour it kept him awake â he eventually lost consciousness and any dreams he had were so loose that the morning sun knocked them away when it woke him hours later.
  He lay there a while, taking comfort in the fact that if the door was unobserved it could be argued not to exist. Eventually curiosity got the better of him and he crawled out of bed and into the hall.
  It was still there.
  At that point even the flimsiest of hopes and arguments were gone and he sank to his haunches and cried for a while; he really couldn't think of anything else to do.
  Eventually, feeling more drained than he had before falling asleep, he walked into the kitchen and made himself a cup of coffee. While it cooled he smoked a cigarette. What else was there to do but to hold on to as much of his normal routine as possible?
  He dressed and examined the door again. He tried the handle, giving a yelp of surprise as static electricity bit into his palm. He shoved it with his foot to see if there was any give in it. The door didn't move in the frame, it remained as resolute as if it were painted on the brick. He touched it again and whipped his hand away instantly, startled by how desperately cold the wood felt, like frozen logs waiting the axe and an open fire. He placed his fingertips to the wood again; this time it was warm. Finishing his coffee he fetched a tea towel to protect him from the static discharge and tried the handle again. It swung the quarter circle on its bolt but wouldn't open. What was the point of a door if you couldn't step through it?
  He went into the lounge, just to get away from it, sat down and lit another cigarette. What to do? What to think?
  He grabbed his coat and went out again, having grown uncomfortable in his flat with the door there.
  After walking in circles, much as he had done the night before, he settled in a coffee shop and drank cappuccino and noise. Half the coffee grew cold as he stared at the walls, trying (and failing) to come up with a single rational course of action. He could think of nobody to call: Jo, even if he had decided to try and talk to her about it, had left no forwarding number. If he did call someone, what would he say? This was hardly a problem that could be solved by conversation.
  He went home.
  He hadn't bothered to hope the door would be gone and it didn't disappoint him. Having decided that there was nothing he could do, he walked straight past it and into the lounge. He turned on the computer and went online, Googling ludicrously for "door appearing", "magic door", "impossible door". It didn't help.
  When the knock came he ran to the front door of his flat with an urge to cry or laugh â it was too brief a sensation to decide which: he was so glad of the idea of company. He opened the door to find the corridor outside empty. As he was stood there the knocking came again and, as the penny dropped, he ran out and down the stairs, finally giving in to a terror that felt almost liberating after the confusion of inaction.
  Standing in the street outside he looked up at his flat and found he was crying again. A few passers-by gave him space as tears turned to shouting and he began to run up and down the street in wild panic.
  It was some time later when he found his thoughts clearing. He was sat in a rough area of park that the council had planted between the urban concrete, no doubt convinced that a little spurt of nature would be an inspiration to the poor bastards that lived there. His hands were bleeding on the palms but he had no memory of the injury. A couple of bits of grit popped out as he picked at the raw skin. He must have fallen somewhere.
  He got to his feet, rubbing at the dirty seat of his trousers, and walked out onto the street. He wasn't entirely sure where he was but if he kept walking he was confident he'd see something familiar.
  It took him a couple of hours to find his way home, by which time he had become so disgusted at the idea of staring at the door that another thought had occurred to him. Stepping out of the lift he walked through his flat and into the kitchen. He pulled open the cupboard beneath the sink and dragged out his toolbox. When they had first moved in he had decided that he would end up doing lots of jobs around the flat. He had bought and filled this cheap plastic box with anything he thought a toolbox should contain. Of course it had sat there since, unopened and unused as the urge had passed almost as quickly as the money spent. He took the hammer and a broad-ended chisel (which still had the price label on it) and marched back to the door. Placing the cutting edge of the chisel against where he imagined the door's lock casing must be, he took a deep breath and began to swing. The hammer chimed against the fat metal end of the chisel and he gritted his teeth, lusting for the sound of splitting wood. It didn't come. After a few minutes he stopped hammering, dropped to his haunches and searched for sign of his work. Some of the paint had fallen away but he had done that much with his fingers. Face pressed tight against the wood, he poked at the gap with his fingernail. There was nothing, not a mark.
  Something whispered on the other side of the door. He heard no words but it was enough to send him running into his bedroom, slamming the door behind him and sitting in the far corner.
  Night fell. He didn't move. The bedroom grew darker and his frantic imagination set to work when he least wished it to. He saw things that weren't there in the shadows thrown across his bedroom wall from the lampposts. The telegraph wires stretched, hanging the misshapen lump of a windowsill ornament by the throat; clouds grew faces that grinned at this desperate man beneath them; a dinner suit hanging by a hook on the door fattened with a dead man's flesh.
  At some point he slept. He woke several times to noises from the hallway. First it was the sound of a woman talking, then a pounding that he took to be something trying to get into his flat from wherever lay on the other side. As a fragile dawn fell through the traffic-smeared glass of his windows he even heard music. Old and crackly, ghost Jazz of the sort trapped on brittle 78's. As the tinny echoes of a horn section long dead permeated the flat he found himself biting his lip with discomfort even as he subconsciously tapped a foot to the rhythm.
  Eventually it grew light and, emboldened by the possibility of sun and the real world, he pulled himself to his feet. He had to lean on the bed as pins and needles rioted in his legs. Once he could move, he tip-toed to his bedroom door and slowly opened it. The door in the hall was as it always was and there was no way of telling if the welcome mat of paint dust that lay across the carpet was the result of his chiselling or the pounding he had heard in the night.
  He ran from his bedroom and out of the front door. He had things to buy.
  The large hardware store presented DIY. as a gleeful pastime. Cardboard cut-outs of cheerful men and women brandished their power tools and immaculate aprons, a world away from sweating hard work. He steered an unreliable trolley up and down the aisles. Young couples idled in front of rows of paint, selecting colours to make a place their own. Middle-aged men weighed up saws and hammers, making a pretence at expertise that everyone â not least their wives â could see for the sham it was. An elderly lady positioned herself on a display toilet, taking in the luxuriousness of its thick wooden seat as she stroked the cool enamel of the bath displayed next to her. "Who wouldn't be happy with this?" she muttered to nobody in particular and settled back to imagine such decadent bowel-emptying.
  He queued up at the wood counter. The constant whine of the band-saw and bored staff banter made him feel sleepy. Men in tatty padded shirts loitered, feeling the grain of wood with their callused thumbs and consulting arcane biro scribbles in their notebooks. He waited and did his best to seem invisible.
  Outside, having paid on a credit card that had given up despairing of its owner, he waited at the taxi rank with his laden trolley, only now aware of the impracticality of his shop. Eventually a driver took pity on him, scratching at rough stubble cultivated during long night shifts and helping load the wood and tools into the back of his people carrier.
  Back at the flat he tipped the taxi driver for helping him get his purchases into the lift. On the twelfth floor he dropped one of the stout planks across the sliding doors to hold them in place as he ferried the rest into his flat. He piled the planks in front of the door in his hall and unpacked the electric drill. He glanced vaguely at the instructions but was too impatient for the job in hand to give them much attention. He slit the sealing tape on a pack of large masonry drill bits with his thumbnail and selected the largest. He spun the drill head, watching it open its mouth like a fat grub and dropped the bit into its jaw.
  He began to drill, a foot or so away from the door frame, spitting the pinkish-brown plaster dust that blew into his mouth onto the carpet at his feet. He measured the holes, drilled the wood to match and began to build his barricade.
  It took him three hours. The things on the other side of the door mumbled to him occasionally as he worked. He did his best to ignore them, drowning them out with the sound of the drill as it bore into the wall or drove thick screws into splitting, plastic-filled wounds. He stood back to inspect his work. The door was now invisible beneath thick slabs of unpainted wood. To think that, the day before, he had been so eager to crack the door open, to see what might lie on the other side. Whatever was in the impossible room adjoined to his flat he couldn't begin to imagine or deal with it â that was the only thing about this he had become sure of, far better to seal it in.
  He decided he would eat something, a celebration of his counter-attack against whatever was trying to invade his home. He microwaved a pasta dish and sat in his lounge puffing at the sickly cheese sauce with lips still coated with sawdust. When the voices from the hall got too loud to ignore he turned some music on and blanked them out with chirpy drum beats and guitar chords. He found himself growing drowsy in his chair, his head nodding as indigestion hissed in his guts.
  In his sleep he heard the sound of the band-saw from the hardware store. Flashing metal teeth gnashed at wood in a spray of sawdust.
  He found himself at the barricade. The noise of the saw was the drone of a blanket of flies that coated the wooden planks. Pressed against them he felt them roll and pop under his fingers and cheeks. They tasted of copper on his tongue. Their buzz was loud enough to be felt as much as heard but he didn't flinch as they squeezed their juice on him, as they rooted through his hair laying their eggs, as they scurried across the wet ice rink of his eyeballs.
  He was sat in the corner of the hall, unsure as to whether he had been dreaming. The flies were gone â he could still taste metal at the back of his throat but that could as easily be the lingering of imagination as the blood of insects. He could hear the sound of something being dragged across dusty concrete. Then a humming noise, a vibration that made his fillings ache. The swing music returned, Glen Miller riding the Chattanooga Choo Choo.