Twelve killing machines stalked through the parched wasteland, and Amelia followed.
         She had tried with no noticeable effect to communicate with them; the machines ignored her as though she wasn't there. They strode through dry, brittle scrub, metal feet crunching on grit and crumbled debris.
         The machines had adaptive skins all over their gunmetal blue bodies. The skins were chameleonic; the twelve man-shaped objects phased in and out of view as the landscape changed, first the colour of red desert, then the peculiar shade of yellow during dust storms, and perfect midnight black when night fell.
         They had been made resistant to military radar. Every surface had the battered, faceted look of a fly's eye. This was how they had withstood all the countermeasures, infiltrated all the army complexes, invaded every city. Near-invisible in the chaos of the twenty-first century, the machines had put an end to everything.
         Amelia, who had spent her twelfth birthday in the flaming wreckage of the last surviving sky-shelter, did not understand their reasoning or their methods. Insects and birds they ignored completely. They were sophisticated enough to know that a plant shaking and rustling in the wind was not a threat. And they did not even acknowledge Amelia, who had seen every other person in the crashed sky-shelter burnt by the machines before her eyes.
         Amelia the sole survivor. Amelia the lost.
         At first she followed the robots through the desert at a distance. Her instinct had been to run in the opposite direction, but what was there left, to the south? The coast, and a few battered seaside towns turned to rubble by the machines' constant bombardment. As far as Amelia knew, there were no outposts in the south, only wreckage and long-dead bodies.
         But to the north...
         Eventually she realised that no matter what she did in sight of the machines, they did not harm her. She could talk to them, scream at them, try to hang onto their legs to stop them walking. She threw stones at them and tried to trip them over.
         Everything she tried only prompted them to make the same whirring, mechanical sounds from deep inside their chests, and the flat, eerie-sounding voices: "NON-HUMAN TARGET. NO THREAT. DO NOT ENGAGE."
         "Why aren't I human?" she demanded of them, and thrashed at them with her fists. "Tell me!"
         But they didn't answer her questions; her actions seemed inconsequential.

         One of the machines was missing an arm. It had difficulty keeping its balance and moved with a curious gait, something like a wounded heron. Amelia thought that it must be damaged inside as well, because it muttered to itself: incomprehensible gibberish, or streams of numbers that at times seemed never-ending.
         "01001110011011110010110101101111011011100 110010100100000011000110110000101101110001000
000110011101101001011101100110010100100000 01101101011001010010000001110100011010000110010100100
000011000010110100101110010001000000111010001101 00001100001011101000010011101110011001000000110
110101101001011011100110010100100000011101 00011011110010000001100010011100100110010101100001011
10100011010000100101," it said, then, "LIVERPOOL."
         Amelia had been born in one of the sky-shelters. She'd always been told that there were only a few shelters left. They ran on fuel that was no longer obtainable due to the toxicity of the irradiated earth and the danger of lingering machines that still scoured every mile of the planet for the last surviving human strongholds.
         The sky-shelters, one by one, had been forced to land. They were immediately set upon by the killing machines, which broke the shelters to pieces. The machines could produce radiation so deadly that it could melt the skin from a person's bones, so Amelia was cautious about approaching this malfunctioning machine.
         "Did you say 'Liverpool'?" she asked.
         "000000," said the machine.
         Amelia had heard of Liverpool. Her father had spoken to her about it in secret.
         "When we have to land," he'd told her, "we'll land near Liverpool. That's the last place where people can be safe."
         But before she could ask another question, the machine batted her aside and continued to limp along, in time with the others.

         For three weeks Amelia followed them at a remove, frustrated at being ignored, guilty for having survived the destruction of the sky-shelter, and grateful to the point of tears for having been spared.
         But the wasteland was cold at night, and she had only her father's battered leather jacket to wear over her school dress. The machines, as soon as the sun went down, always constructed a fire. This didn't strike Amelia as unusual. She didn't wonder why they stood motionless in two tight concentric circles around the bonfire they made.
         Nightly she approached the dancing werelight glimpsed between the pillars of the frozen machines. They stood close together and she had to push her way through them to get to the fire. For several hours, until she fell asleep, she could be warm.

         The river had burst its banks, flooding the fields for miles around. They trudged through the muddy water, never deviating. For a while Amelia felt safer in the presence of the machines, unstoppable as they seemed to be. But she grew to feeling sick, and had become faint from starvation. The robots did not need food. They didn't drink. The river water was like swill, and Amelia didn't dare try to swallow any.
         For days she prayed that it would rain, because she knew that on the sky-shelter there'd been dozens of funnels set up to catch rainwater to use for drinking. Rainwater was safe, even if the clouds were angry red and the rain passed through permanent canopies of ash to reach the ground.
         But no rain came, and the thought occurred that she was going to die.
         Things moved under the surface of the river. One lucky glance won her a glimpse of something long and thin rippling beneath the water: the tail of something big and reptilian. She hoped that whatever prehistoric monster lived in the mire would be put off by the presence of so many metal legs in the water.
         But the second time she heard splashing, it wasn't an animal. She saw a human face peering out from a tall thicket of bamboo-like reeds--another person! But even as she saw the human eyes widen with surprise and joy, much like hers must have widened, the machines reacted.
         Amelia screamed as the machines splashed towards the thicket. The stranger, a man, knew that he'd been spotted and made to run. He needn't have bothered. The adaptive skins on the legs of the machines were capable of thickening or narrowing in places, and formed stern-like points that allowed the robots to move through the cloying mud with ease. The nearest machine caught the man by the neck with one hand. It was the first human being she had seen in a month.
         "No!" she shrieked, splashing messily towards them as fast as she could. She jumped to pull the robot's arm, but it was too tall. "Leave him alone!"
         "HUMAN TARGET," said the machine.
         Amelia tried to close her ears to the crunching, popping sound of the man's death. She was aware of what felt like warm mud spattering her face, and then of a big splash. A smaller splash followed, somewhere very close to where she was standing.
         She opened her eyes to see the head carried behind the thicket by the moving water, and the body surrendering its blood to the current several feet behind.

         A week later, as they crossed the charred ruins of a park, the one-armed machine stopped dead in a heap of ash and grit. The other robots seemed to recognise immediately that one of them wasn't moving with the group. They turned to see what the matter was.
         Amelia hid behind the stationary machine. The others watched, rigid and faceless. They had rings of glass around their heads, within which light moved round and round like a constantly roving eye. The lights slowed and stopped at the front of their heads, crackling blue-white like lightning.
         "EXAMINE UNIT."
         They approached in unison. Amelia shrieked and ran away to crouch behind a portion of iron railing that had survived the park's destruction. The machines surrounded the broken unit and looked at it.
         "EXAMINE UNIT. IS UNIT OPERATIVE, YES / NO?"
         There was a minute pause before a second machine responded: "NO. CAN UNIT BE FIXED, YES / NO?"
         Four or five robotic hands reached out to caress the motionless, one-armed machine. Its adaptive skin rippled as it attempted to process the myriad moving colours and reflections alongside it. Within a moment, the skin seemed to give up and turned a crusty brown that shriveled and shrank against the machine's inner structure.
         "NO," said one of the others. "CAN UNIT BE SALVAGED FOR SERVICEABLE PARTS, YES / NO?"
         Some of the machines were badly dented. Others had tears in their adaptive skin and thick flaps, like rubber, hung off them in places to reveal smooth silver chassis.
         "YES," they said in unison.
         They knocked the inoperative machine to the ground with their fists. One machine with a shattered glass sensor-strip tore off the head as another peeled away the skin from the stomach. The skin flickered to the colour of desert, then sky, then turned wrinkled grey-brown again as it hung limply from the machine's oily fingers. A third machine pushed its hand into the empty shoulder socket, twisted, jerked, pulled free with a fistful of wiring connected to a few lumps of interconnecting metal dripping with lubricant.
         By the time they set off once again across the wasteland, Amelia had already seen the broken unit reduced to four or five pieces of hollow exoskeleton and oily heaps of tubing and rubber-coated cables. The headpiece was an empty helmet, the remaining hand a knot of twisted steel bones.

         Amelia wanted to ask the machines to tell her whether they were really going to Liverpool. There was no point in asking what they intended to do when they got there. But she had no way of stopping them, and no way to find Liverpool by herself. Even if she had, she could not move faster than the machines, which strode down the road of fractured concrete at a pace Amelia found difficult to match.
         She could only follow them to watch the Liverpool shelter burn.
         It was difficult for Amelia to think around the situation. She was young and not accustomed to making her own decisions. She had always been told what she should or shouldn't do and then she chose to obey or not obey. Her parents had been kind, busy, worried, loving people, and Amelia had trusted them. But the robots were emotionless and cold and could not be relied upon at all.
         Though she'd determined that the machines did not acknowledge her as human, it didn't occur to her to wonder why. She only knew that she did not know the answer and that the only other things around--the machines--would not tell her. If she met somebody else, then she would ask him or her. But she didn't have the will to figure it out, and every day in the wasteland was a constant barrage of new information.
         A few days later, at the start of her fifth week trailing the machines, it began to snow.
         It was dirty, foul-tasting snow that dropped vertically and heavily straight to the ground. It didn't settle, but dissolved into thin muddy water that soon collected into shallow puddles. An acrid stink rose up from the ground, sulphurous and sharp.
         It didn't help Amelia's stomach, which was now giving her stabbing pains whenever she straightened up too much, but it would keep her alive for a day or two longer. Her guts were shriveling up inside her like an old apple. It was not the hunger, but the poisonous earth. A large part of her mind knew this, and railed at the contaminated snow that melted into trickles of water on the domed heads of the machines.
         A sudden, loud noise cracked in the muffled air. Amelia looked up with a start. A second shot rang out, crack!, and something ricocheted off the shoulder of the leading robot. Something broken inside the joint buzzed noisily then ground to a halt. The machines stopped dead. They turned their heads.
         Crack! Another gunshot! Amelia, who, lost in her thoughts, had caught up with the machines without intending to, ran to the nearest ditch to watch from over the mound. This second shot connected again with the machine, but it was ineffectual. Twelve killing machines converged on a downward slope fifty yards away.
         "Forget it!" Amelia heard someone shout. The word was softened in the heavily falling snow. "Run! Run!"
         Three figures scrambled away from the advancing machines. They dashed towards where Amelia was hidden, with their boots splashing in the dirty melting snow. She saw surprise mingling with terror on their faces as they spotted her, so close to the enemy.
         The first to die was a woman who reminded Amelia of her mother: dark-haired and full about the hips, with the same flapping layers of brown clothing. She was cut in two by a jolt of crackling blue light from one of the machines, and the pieces of her lay sizzling in the melt-water.
         The other was a young girl, maybe not five years older than Amelia herself. She was holding the hand of a younger boy, Amelia's age, and screaming for him to run, to run. They were almost on top of Amelia when the machines caught them.
         Two shimmering-blue hands grabbed the older girl's coat. She cried out hoarsely and squirmed, willowy beside the stocky immovable bulk of the machine. She was only a teenager; the machine pulsed with light and heat, and the radiation burned the skin away from her flesh. The flesh and subcutaneous fat bubbled, ran in pinkish-white streams from her body, then evaporated. The bones crumbled to dust in the machine's steely fingers.
         It turned its fizzing sensor-eye to the boy. Amelia screamed. The boy had already met her gaze, and she knew with certainty that she did not want this boy to die. She did not want the boy to die.
         The machine seemed to examine him for a second, its faceless head tipped in his direction. The other machines materialised through the veils of thickening snowfall. For a full minute they were motionless in a circle around him, as stiff as statues. The boy was whining from deep in his narrow chest, struggling in the machine's grip.
         Even with all sound muffled by the dirty snow, Amelia could hear the clunking of strained gadgetry within the machines. Then they seemed to relax.
         "NON-HUMAN TARGET. NO THREAT. DO NOT ENGAGE."
         "Fuck you!" the boy screamed, and lashed out at the machines with his legs. "You stupid fucking robots! There's nothing wrong with me! Fuck you!"
         The machine whirled around. The sensor-eye crackled like trapped lightning. The boy froze and paled, his mouth hanging open. Then the machine turned away, and said again: "NON-HUMAN TARGET."
         Together the killing machines left. Quiet splashing footfalls faded away into silence.
         Tentatively, Amelia approached the boy, who knelt crying in the snow. "Are ... Are you okay?"
         "Leave me alone!"
         "Why didn't they kill you?" she asked. Her voice was croaky; she hadn't spoken in a week. "What's the matter with us, that makes us not human?"
         "There's nothing wrong with us," he snapped, and rubbed viscously at his eyes and nose to erase the evidence of his tears. "Stupid machines. They don't know nothing."
         "They think we're not human."
         "Sometimes they kill kids younger than us. Sometimes they leave grown-ups alone. They don't know what's human and what isn't, they're stupid and broken."
         He picked himself up, tried ineffectually to brush away the brown, wet stains on his jeans. He had mittens threaded through the sleeves of his coat on a string, and he put them on. Seeing that Amelia didn't have any, he seemed momentarily sympathetic, and then hardened.
         "What's your name?" she said.
         "James. What's yours?"
         "I'm Amelia."
         With a mittened hand he fluffed the snow out of his scruffy auburn hair, then about-turned and marched after the machines.
         "Where are you going?" Amelia asked, taken aback by his sudden vehemence.
         "I'm gonna go around them robots and back up to Liverpool, where my Dad is. Then we're gonna shut the doors and put all them locks on and live down in the shelter where they can't get to us."
         "But do you know the way?" "I know them robots is going there. That's what Jackie said. And Lizzie said she thought they was going there too. It's the only place left."
         Amelia stopped in the snow for a second, watching James walk away. Then she ran to catch up, and they walked together on top of the tracks of the machines.

         By dusk, the machines dispersed as they always did to gather fuel for a fire. They did this with urgency, taking great strides across the burnt-out parkland or through the flattened towns to locate the best firewood. Mostly it was old furniture--as far as Amelia could tell, the whole of the country had once been city pressed against city, for miles--but occasionally it was a huge branch dragged through the debris, or armfuls of wooden fencing smashed to splinters.
         As the days drew on, the night fires grew bigger. The machines would press close to the fire, leaning inward almost to the point of toppling. Some internal mechanism prevented them from falling over. It became very strange watching the machines do this, and to see their adaptive skins flickering and morphing in front of the orange flames.
         Then, gradually, the fires started to go smaller again. The machines had taken to walking more slowly during the day, until Amelia and James could even stop and rest on a grassy patch, or investigate the ruins of an old building long ago gutted by radioactive fire. The machines would walk on, ponderously, as their followers sat and talked.
         Sometimes the talking would go on for hours. It wasn't about anything in particular. Most mornings, Amelia couldn't even remember what they'd been up talking about the night before, by the dwindling, insufficient fire.
         The nights turned bitterly cold; the sun during the daytime was not enough to warm the two children. They huddled together in the twilight hours between daylight and the minute the machines lit their fire with bursts of radioactive lightning. When the fire was crackling away, they crept in between the statuesque metal shapes and nervously warmed their hands until the little flames died to cinders, then went out.
         And then, a week of slow walking later, the machines made their fire, stood still all night as though asleep. Amelia and James woke up gently instead of to the sound of shifting machines.
         James circled the closest of them curiously, his hand stroking round and round the cylindrical body of the lead machine. It didn't move. It wouldn't respond. There was not an iota of life within it.
         "Thing's dead," he said simply. He looked Amelia in the eye. "We're free of 'em."
         Amelia looked first at the motionless robot, then at the cooled embers in the centre of the fire, grey and lifeless.
         "What's the matter?" said James.
         "They're good as dead."
         "Yes?"
         "So," she said, beginning to cry, "who's going to show us the way to Liverpool?"

         It took a day for them to decide what to do; that the best and only solution was to wait and see whether the machines would wake up again.
         "We've got no idea how long it'll take," said James. "It could be ages."
         "We don't have a choice, do we?" "If we just keep heading in the same direction..."
         "How many times did they find a bridge over a river when we couldn't see one? Or look like they were going a completely different way when they were just going around a big poisonous lake we would've walked right into?"
         "We got to try," he said quietly. Then, "I wish Jackie was here."
         "She was your Mum?"
         "She were Lizzie's Mum. Lizzie was the girl."
         "Oh."
         "So we can't go anywhere until they wake up," he agreed. "But when will that be?"
         She looked up. "Maybe something to do with the sun? Strong light?"
         "But it won't start getting properly bright again until spring!"
         And so it was that they spent night after night in the company of lifeless hunks of blue steel and advanced plastics, who became their scarecrows in the night against the mutated birds that survived the worldwide fires.
         They had to collect their own firewood, which got harder with each passing week. At first it was old chairs and desks pulled from collapsed buildings along the road, which took ages to catch alight and were horrendous to keep burning. Later they had no choice but to climb trees and kick at split branches until some of them fell loose, then heave them back to the circle of dead robots.
         It did snow during the winter, but it was the dirty snow incapable of settling. The worst the weather threw at them was the frost, which snuck up on them in the dead of night and made them stiff and achy beyond the reach of any tiny bonfire they could get going.
         "What if they never wake up?" asked Amelia one bitterly-cold morning.
         "They will. And then they'll show us the way to Liverpool ... but blow it up before we can get inside."
         She said, "We'll never find it without them, though."
         "Then we'll just have to wait," said James, and threw another smashed-up chair on the fire.

         It was about the time that she started throwing up blood that he told her, "I think today's my birthday."
         She looked up, feeling sore about the stomach and legs. There was pink on the back of her hand where she'd wiped her mouth. "What?"
         "Think it's my birthday. Today. I was trying to count the days, using the moon, and my birthday's the first of February, and this is the fourth moon..."
         "So what do you want?" she said, and sat down on the frozen earth. "A present? There's a bit of bark we haven't eaten yet."
         He shrugged. His eyes, she had come to realise, were always brighter in the morning-time. The auburn hair she had come to identify him by had grown long about his ears, between those eyes. They looked at her right then, sharp as shards.
         "If you want," Amelia said, "I can get the wood today, and you can watch for the machines waking up."
         "Hmn." He didn't seem like he liked that idea. He didn't seem like he wanted to be away from her that long.
         "If we both got the wood, we'd be done in half the time," he said.
         With the chill of the morning air, her abdomen had become a little less painful. It had already been five days and she hoped that the bleeding would already have stopped.
         "And then what would we do?" she asked.

         The day they found the first buds was the day they returned to the camp to find the machines absent. There were plenty of footprints, and some confusing marks in the dust as though upon waking the robots had tried to describe dreams in the earth, but not a single unit to be found.
         "They woke up," said James, distressed. "We missed them!"
         "We've only been gone a few hours, and they'll be slow." Amelia was sure that she was right, and that they could catch up. James seemed to think her certainty appealing, and invigorating.
         They set off quickly towards the northern rise, where they had come to learn how the regular tide of the river brought in fresh water and living fish suitable for eating. It was there that they saw eleven machines moving in two columns through the ruinous landscape, oblivious to all the familiar scenery around them.
         It was slow going at first, letting the stiff and malfunctioning robots guide them towards their destination. They had no other choice but to follow. It became a certainty that they were getting close to Liverpool, but there was no way to know for sure, and all they could do was keep each other warm during the cold nights. The machines were too sluggish to gather adequate firewood to keep all of them in good comfort, and their followers kept a much greater distance.
         "We could follow them forever, and never get there," said James. Lately he had taken to trimming his hair every week with a knife he had found, apparently for Amelia's sake.
         She gave him no reply but a quick kiss.
         Four days. Four days after this, when James first became ill from the toxic earth and Amelia's hair began to come away in clumps in her fists.
         And when they saw the blinking radio tower in the night sky about Liverpool.
         "We're here," she croaked. "I think we found it, my love."
         Panic filled James" eyes. "A radio. No wonder they knew how to find it. Stupid!"
         "But we relied on them to bring us here," she pointed out.
         "And now they'll kill everybody there before we can say hello!"
         She pulled the rags of her too-small school dress closer over her shoulders. Her eyes kept going to the radio tower, where a powerful bulb blinked on and off in the gloaming.
         "Or..." she said.

         It was James who drew the short straw and had to climb the rickety radio tower. It took him a long time; long enough for the machines to get closer. Then, when the sun was at its highest, Amelia saw a tiny figure atop the mast waving a metal box with a flashing light, and shouting, "I got it, yo ho!"

         They ran, and yet the machines stalked behind them with something approaching disinterest.
         "We'll be okay on the river," James said.
          "Why?"
         "Because there are boats on the river. Jackie told me."
         "You know how to use a boat?"
         "It just floats, doesn't it? The river takes us the rest of the way."
         The warmer air thawed the permafrost around the estuary, and spread the marshland closer to the edges of the demolished cities. Further east, the flattened suburbs of Liverpool were brown-grey streaks on the horizon. The sky was a blanket spread with stars.
         On the misty quay were vessels of all shapes and sizes, most capsized against the concrete docks. In the centre of the canal were great scabs of flotsam, congealed on the silver Mersey. And cloistered amongst mossy barrels and tangled plastic: a motorised boat.
         She found a way to convince him to swim to the boat by himself, and bring it back. The motor was useless, of course, but there were oars, and despite the many clots of garbage the river still moved towards the sea.
         "I can smell the salt!" she told him as he brought it to the riverside.
         "Good."
         "Are you mad with me?" "I'm bloody freezing."
         She climbed aboard. The beacon winked at her, red and black, in the darkness within the modest cabin. "Is it still working?"
         "As far as I can tell."
         "Won't it float out by itself?"
         "Nope."
         They sat atop the cabin. The roof was covered in rubber matting that stopped them slipping. The oars were long and cumbersome, loaded as they were with moss and a kind of brown, clinging weed, but they were intact.
         "How long do you think they'll follow us?" she asked, and put both her arms around one of his. He would row for the first hour, they'd decided, and she the next.
          He shrugged. "Maybe forever."
         "Out to sea?"
         "If we're lucky. Then the outpost will be safe and they'll have no way to find it again. I suppose one day we can ditch the beacon and try to find our way here."
         "Hmm," said Amelia. Neither of them believed that they would be able to find Liverpool again, once they'd been gone long enough. The world was changing too fast.
         The river widened. The stars seemed to be bigger out here. The moon was a white garden in miniature, fuzzy around the edges with cloud.
         The river widened and widened, and didn't stop.
         Amelia thought, It's the sea already.
         And soon enough, it was the sea.