THEY WAITED UNTIL darkness had fallen and travelled without lights. Alice led the way over the next ridge and then down into a forest. She seemed at home there, pushing through the undergrowth and stepping over tree roots as if it were daylight. All the boys could do was try their best to stay close, tripping and stumbling as they went, with their backpacks jostling on their backs. The forest smelled just as it did back home: the rotten sweet smell of old dirt and decaying leaves, and the subtle sharp scents of the undergrowth. Stefan’s lungs burned and his shoulders ached from keeping his hands high in front of his face to push away unexpected branches.

They finally stopped beneath a huge tree, and it was only then that Alice allowed them to turn on their headlamps. The forest moved with the beams of their light, and disappeared into darkness far higher than their lamps could reach. Next to them, a small, fast-flowing stream gurgled and chattered. Alice dropped to her knees at the water’s edge, splashed her face and then dipped her mouth into the current, lapping greedily the way a dog might. Arlo and Stefan copied her actions. The water swirled about Arlo’s face and bubbles tickled his nose, but he didn’t mind. He had never known water to taste so good, so sharp and fresh. He could feel it spreading through his body, revitalising every part of him.

‘How far to camp?’ Stefan asked, water dribbling down his chin and cooling his neck.

‘Not far at all,’ Alice said.

‘That’s not an answer,’ Stefan complained. ‘You’re very good at not answering questions.’

‘We’re here,’ Alice grinned. ‘This is it. This is our camp.’

Arlo and Stefan looked about, their faces full of doubt. ‘It doesn’t look much like a camp,’ Arlo said.

‘I know,’ Alice replied. ‘That’s the point. Okay, follow me.’

She turned to the huge tree. Its buttressed base was as wide as a small house, and she took two steps to her left and then disappeared.

The twins looked at one another then rushed forward. The gap Alice had squeezed through was all but hidden from the outside, appearing to be little more than a bulge in the trunk. The hollow was wider at the bottom and the boys crouched, crawling on all fours until it opened out into something like a small cave. Alice had hung her headlamp on a branch overhead, making a sort of lantern. The walls were hairy with tree fibres, and underfoot was a frame of branches covered with ferns. Along a twisted root that served as a kind of shelf, was a row of tinned food, an old pot, eating utensils and a water bottle. Alice crouched by an old canvas pack and carefully unzipped it.

‘Get all your food out,’ she said. ‘I’m not going to eat it. We just need to keep it locked away, or rats will come looking for it, and that will keep us awake.’

There was a lot to learn.

‘How long have you lived here?’ Arlo asked her.

‘I had to wait for the next full moon before the tunnel reopened,’ Alice answered. ‘It gave me a chance to look around.’

It was one of those sentences that hinted at a hundred more to come. ‘How did you have enough food for a month?’ Arlo asked.

Alice shrugged. ‘Mr Williams made sure we took supplies with us. I think he knew we might be trapped here. It wasn’t enough, but I’m used to not having enough. This is your bed for tonight, by the way.’ She kicked at the ferns. ‘It’s not too bad, as long as it doesn’t rain.’

We should have brought pillows, Stefan thought to himself. She should have told us to bring pillows. He opened his backpack and pulled out his tightly rolled sleeping bag. His watch was no good to him here, it kept time for a world that for now didn’t exist, but they’d been walking for hours and he could have slept on concrete if he had to.

‘What are you doing?’ Alice asked.

Stefan paused. ‘Um, just getting ready for sleep. Or do you want us to take turns keeping watch again?’

‘We’re not sleeping yet,’ Alice said, as if she considered the idea ridiculous. ‘We have work to do.’

‘What sort of work?’ Stefan asked.

‘Scouting. But you’ll need fuel for that. Here, have one of these.’ She pulled down three cans from her small stash, handed one to each boy and kept the other for herself.

‘What is it?’ Stefan asked.

‘Food,’ was her only reply. ‘I hope you remembered spoons.’

The food was, in fact, rice pudding, which Arlo had tried only once before and pronounced disgusting. This time its thick creamy sweetness was delicious. He ate it too quickly, not thinking until the last mouthful that he should be savouring it.

‘Good, right?’ Alice said.

‘Amazing.’

‘Arlo, you’re on dishes. Wash the cans out in the stream. Take your light and let me know if you see any eels.’

‘Why,’ he asked. ‘Are they dangerous?’

Alice shook her head. ‘Tasty.’

With the cans washed out, and the eels sensible enough to stay hidden, Alice explained their next task. It occurred to Arlo that she liked drip feeding them information, that it kept her feeling in control. They were older than her, by at least six months, and bigger, and there were two of them, and they were the ones doing her a favour—yet still there was no doubt she was the leader. He knew it made sense, she was twice as tough and determined as they would ever be, and it was her sister being rescued, but still he resented it a little bit. Just as he resented hearing that they would be walking for another hour through the bush, cutting back behind the swampland and then down to the docks, where they would somehow make their way across the harbour to the headland.

‘Where there’s a big tent,’ Arlo said.

‘Yes,’ Alice nodded. ‘Where they’re keeping Jackie.’

‘Are we rescuing her tonight?’ Stefan asked. ‘Wouldn’t it make sense to wait until we’re more rested?’

Alice gave a small laugh, weighed down with sadness. ‘If it was that easy, she would already be free. Tonight I just want to show you where they’re keeping her, so you can see what we’re up against. We’ll get back before sunrise. It’s safer if we do most of our sleeping during the day. That’s the most dangerous time to be moving about. And the Academy carriage doesn’t come until late afternoon.’

‘What’s the—’

‘Later. We’ve got walking to do.’

Alice made them change into clothes she had stolen—from where she didn’t say. The fit was imperfect but she assured them that didn’t matter. The important thing was that these were the clothes other children their age would be wearing: button-up shirts, long sleeved and made of a coarse off-white material, tucked into heavy itchy trousers. She had a cap for each of them too, and heavy-soled boots that pinched at the sides of Arlo’s feet, while Stefan said his were too broad.

Arlo’s legs ached and he could feel blisters beginning to form at his heels. His shin throbbed from a collision with a fallen log and his cheek stung with scratches. Most of all he was tired. His whole body was heavy. He remembered the time his father had taken them to the top of the local mountain ranges, how he’d promised them they’d find a second wind, but that had never come. This felt like that, only without the chocolate or daylight, or sense of safety. But he didn’t complain, and neither did Stefan. There was something about Alice that made complaining feel silly.

The walk was no easier than before, but somehow the pain grew less sharp with the hours, until it was like a simple blanket of discomfort to carry with them.

They finally emerged from the trees and into the smells of farmland. Alice dropped to the ground and pointed to the harbour below, still and sparkling in the moonlight. Stefan tried to match the view with the world he knew, tracing in his mind the motorway, which at this hour would form a fairy necklace of yellow lights stretching northwards, and the point where the railway bridge crossed over the deep swift waters of the inlet. The moon itself was strange, he now realised. Not in size or shape, but in the dark markings of its surface. Not that he’d ever looked at the moon that closely before, but he could tell this was different.

‘Yeah, weird eh?’ It was Arlo’s voice, not in his ear, but inside his head. Stefan gave a start and looked at his brother, who did not appear to have noticed anything unusual.

Apart from the moon, the only detectable light source was the distant tent, which glowed faintly yellow on the raised horizon.

‘It would take five hours to walk around the harbour,’ Alice said, ‘and we’d be trapped on the headland in daylight. Our only option is to go across the water.’

Neither boy spoke, the obvious ‘how?’

Alice answered anyway. ‘I know where there’s a rowboat we can borrow,’ she told them. ‘We just have to be very very quiet.’

‘By borrow you mean—’

‘Steal. Yes. We’re going to steal a boat.’ Her voice was curt and impatient. ‘Hurry up, the moon’s already peaking.’

The rowboat was tied to a small wooden dock connected to the main port area by a series of walkways of various sizes and states of neglect. Alice said it was too risky to walk openly along the jetty, or even crawl, and insisted they remove their boots and socks, roll up their trousers and wade out to the boat.

The mud was silty soft and oozed between their toes, and sharp shells dug into the soles of their feet. The depth, predictably, exceeded the height of their rolled-up trousers and they were soon wet to mid-thigh and, despite the mild night, beginning to shiver.

Alice urged the boys up into the small wooden dinghy and set about untying its mooring rope. Further along, on a neighbouring jetty, a dog barked and the boys ducked down in the boat, frozen.

Alice continued working the knot, apparently unfazed. ‘Just a dog,’ she whispered, as if dogs couldn’t cause any trouble.

‘Done!’

There was a sudden splash and she rolled into the boat.

‘Okay,’ she grinned. ‘Pass me the oars. Or would one of you prefer to do the rowing?’

I’m glad she’s on our side, Stefan thought, and immediately Arlo’s voice reappeared in his head. ‘Same,’ it said. Quite distinctly, and yet utterly silent.

Are we—?

Reading each other’s minds? Yes. I think so.

That’s so strange.

Everything here is strange.

For the first time since the tunnel had opened, Stefan found himself smiling. Arlo took his hand and gave it a short sharp squeeze. He was right. Whatever happened, they would have each other.

The theft proceeded without incident. The owner of the boat, along with every other resident of this strange settlement, was apparently asleep. They quickly crossed the calm stretch of water. Alice’s rowing was as steady and purposeful as everything she did. They hauled the boat up onto a shingled beach and dragged it further into a small clump of bushes and out of sight. Alice pulled the boys close for their last instructions.

‘After this it will be too dangerous to speak,’ she told them. ‘If you hear anything from me, it will be a single word, ‘Run!’ If you hear that, you must split up. Do not come back here to the boat. Run as fast and as hard as you can and then go to ground. If you are lucky and they do not find you, wait until tomorrow night and then make your way back to the camp. You’ll have to go around the harbour—they’ll be watching the water. Do you understand?’

Arlo nodded. He understood, but he did not want to think about it. Whoever it was he would have to outrun he doubted he would manage it, not in these clumsy boots. And even if he did, there was no way he would be able to find the camp again. His only hope was that it would not come to that.

‘Follow me up through a narrow valley,’ Alice continued. ‘We’ll come out higher than the mine, and then make our way back along the ridge towards it. You will see guards patrolling the perimeter. Move when I move, even if you feel it isn’t safe. You have to trust me. There is a chute near the back of the tent, where rubbish is collected. We’ll climb up that and into a bin. Look up and you will see all you need to see. We’ll leave the same way. I lead. You follow. Is there anything you want to say? Otherwise we don’t speak again until we are back here. Understand?’

Do you understand? Stefan messaged in his head.

Kind of, Arlo silently replied. It was such an odd feeling, these messages passing between them, that he had to fight the urge to giggle.

‘And if you’re passing twin messages,’ Alice interrupted, ‘now would be a good time to stop. I’m pretty sure that’s how we got caught last time. I think the guards can hear them.’

As they climbed their way up the valley, the sounds coming from within the huge tent grew louder. Here was the one place that didn’t close for the night. Alice had called it a mine, Arlo remembered, and so he imagined the clunks and whirs and whooshes to be coming from a huge steam-powered drill, augering its way into the earth below. But what would they be drilling for, and what did that have to do with Alice’s sister? Wondering took his mind from the tiredness of his legs and the emptiness of his stomach. Beside him Stefan moved with the same heavy footstep

s. Alice remained light on her feet, watchful as a meerkat, crouching, signalling, moving again.

Despite the intensity of the noise, it was still a surprise to see how close they were to the tent when they emerged from the bush. They lay flat on the ground, taking in the great scale of it. It was as large as a town hall, with hundreds of arm-thick ropes tethering it to the ground in a treacherous obstacle course of pegs and knots. It was made of a dirty white canvas that glowed yellow from the fires within. Stefan noticed movement to his left and buried his head in the cool grass, one eye warily watching the dark form of a sentry walking within a stone’s throw of their hiding place.

The guard stopped suddenly and so did Stefan’s heart. He felt his brother’s hand on his, clawed in fear. Beside him, Alice watched intently, her lips moving silently as she counted out time. She moved without warning, without looking back, trusting them to follow. The boys stayed close, running crouched behind her to the exact point where the guard had disappeared from view.

The chute was made of rough-cut timber and ran beneath a flap in the heavy canvas. It was as wide as their shoulders and smelt of the sludge that clung to every surface. They crawled on, Alice first, then Stefan, and Arlo last. Within the tent the sounds clarified into their separate parts, metal on metal, the grinding of rocks, the roaring of a furnace. A thick heat blasted over them and Arlo dropped his head, breathing deeply to steady his shaking. They moved more slowly, heads down, exposed.

The chute ended inside the tent at a large bin the size of a dump truck, made of thick planks bound with rope. Alice climbed in and slipped down feet first, disappearing from view. The boys followed as quickly as they dared. Arlo shuddered with a wave of claustrophobia. If anybody saw them now, they were trapped. The bin was only a third full, its load a jumble of broken timber, crushed metal containers and filthy rags, and beneath it some kind of slurry. Alice pressed her finger to her lips, as if the boys needed reminding, and then pointed above them.

There, suspended in mid-air off the end of what looked like a medieval crane, was a metal cage. It was so small that its occupant was forced to sit with her knees to her chest. Her eyes stared blankly ahead, her long hair was lank with sweat, and her exposed arms were terrifyingly thin. Had he not already been told, Arlo might have missed the fact that she was the identical twin of the fierce girl beside him. He looked at Alice and read the pain in her face, imagined it rushing through her like a darkening storm, gritting up the ridges of her angry soul. A single tear formed at the corner of Alice’s eye and she did not brush it away. Arlo saw the muscles pulsing on her jawline, and the resolve harden in her heart. She turned quickly, just once, to check the boys had seen her sister, trapped and lonely, broken. If an animal had been held that way, people would have protested about the cruelty. Arlo’s heart ached for the prisoner and he knew in that moment the very thing Alice had brought them here to understand: that he could not rest until the girl was rescued. Whatever this world was, whatever the magic that had brought them here, this was his job, and his brother’s job too. This was what they had to do.

Again Alice counted silently, her lips shaping each second. Then she leapt, as quick and graceful as a cat, up the side of the bin and head first down the chute. Stefan followed, with none of her elegance but all of her speed. Arlo propelled himself close after, relieved to leave the heat and noise and confusion behind.

Alice crouched at the bottom of the chute, looking to check she still had both boys with her, then nodded and ran back towards the bush. Stefan ran hunched, his shoulders tight, waiting the whole time for the cry that never came: ‘Guards! Guards! Twins at the eastern wall!’