It was a small vessel, about the size of a rowing boat, but it was scooped up at the front as if it had been carved into a specific shape. There was a cloaked figure sitting in the boat who, every now and again, dipped a wooden staff into the water to ease the vessel across the swamp.

Fox didn’t cower away. And neither did Heckle or the sloth. The glasswing butterflies had led them here, which meant that the Forever Fern was probably somewhere beyond this swamp, and now it seemed there might be a way to cross the water, after all.

The boat was halfway across now and Fox saw that it was painted white and the prow was actually carved into the elegant neck and head of a flamingo.

‘I come in peace,’ the cloaked figure said. It was a woman’s voice, lilting and strong, though Fox couldn’t tell whether it belonged to someone young or old. ‘I am the last Unmapper left in these parts,’ the woman called. ‘I have been hiding out over here and waiting for you.’

Fox took a very small step backwards and Heckle fluttered up onto her shoulder. Goldpaw hadn’t mentioned any Unmappers living in the Bonelands.

‘I am here to help you cross the swamp and continue your search for the Forever Fern,’ the woman went on.

The boat was a stone’s throw away now, but still the figure didn’t lift her hood back from her face. She kept her body completely hidden.

Fox couldn’t help wondering how the woman had known that she would come this way. Even Fox herself hadn’t known she’d end up at the swamp until a few moments ago. The sloth tightened his grip round Fox’s neck, which made Fox take another tiny step backwards.

Heckle stiffened on her shoulder. ‘Heckle is feeling worried because she can’t read the Unmapper’s thoughts…’

The boat was approaching the shore now and overhead Fox noticed that the flamingoes were flying back towards them, too. She could hear that their wings were beating with an unusual sound: a clattering rather than a whrum. With one final push, the cloaked figure let the vessel glide right up to the wooden jetty in front of Fox. The Unmapper stretched out a hand to pull herself up onto the pontoon and the air turned suddenly cold.

The Unmapper had fingers, but where skin should have been at her wrist there were feathers. Black ones that shone like oil.

She stood on the pontoon and though the hood of her cloak was still draped over her head, Fox caught a glimpse of a yellow eye that burned with malice. And, as soon as Fox locked eyes with the figure, the magic that had been holding the whole scene together – the magic that had made Fox feel like the boat had come to help her – vanished.

This boat had come for Fox, but not in the way she had hoped.

The boat’s planks transformed into bones. And when Fox looked up she saw that the flamingoes soaring towards them were now vultures that looked also to be made entirely of bones. Creatures stirred in the swamp around the boat, too, and Fox’s eyes widened as the heads of several large black crocodiles broke the surface of the water.

But most terrifying of all was the figure on the pontoon. No longer feeling the need to hide, it threw back its cloak and Fox screamed at what she saw: the body of a woman, but a woman covered in black feathers, with talons for feet, a long pointed skull over her face and two shining black wings tucked in at her sides. Heckle hadn’t been able to read the Unmapper’s thoughts because this was no Unmapper. This was a creature filled with dark magic.

This – Fox realised – was the harpy, Morg.

‘And so, girl from the Faraway, we meet at last,’ Morg sneered.

Fox didn’t wait to hear any more. She turned and ran, legs pounding, arms pumping, with the terrified sloth bouncing on her back and Heckle flapping in front as together they rounded the swamp. It was too late for the doubleskin mirror: Morg’s eyes were pinned on Fox so she couldn’t melt into the forest unseen. She fled, the crocodiles following her every move, skulking through the water with teeth bared, while up above the vultures trailed her on skeleton wings.

And down on the forest floor, scuttling round the bank of the swamp like a large, deformed beetle, came Morg. Her wings were bristling with dark magic now, which she had put to use by disguising the flamingoes and the boat, and which she planned to use again as soon as she closed in on the troublesome girl. But those wings were not yet strong enough to grant the harpy flight. Instead she scuttled over the ground because she’d let a Faraway child escape once before and she wasn’t going to make the same mistake twice.

‘Give up, little wretch,’ the harpy crooned. ‘There is no one left in the Bonelands to help you now!’

Fox threw a look over her shoulder to see Morg churning up the reeds with her talons and tearing round the swamp after her. She was gaining on Fox, no matter how fast she ran, and though the weight of the sloth and the satchel were slowing Fox down she refused to part with either.

So frightened was Fox by the harpy on her tail that she didn’t see the vulture that was dive-bombing towards her. The first she knew of the attack was a punch to her shoulder as the bird rammed its weight into her. Fox stumbled backwards, then tripped over a log, but forced herself up and carried on running. Another vulture was making a beeline for her now and, though Heckle tried her best to ward it off, the bigger bird batted the parrot aside, charged on towards Fox and pinned the girl to the ground.

The harpy laughed. ‘You see? There is no escaping my dark magic in the end!’

Fox pushed and shoved, Heckle pulled and tore, but the vulture’s hold was firm and Morg was drawing closer and closer. Then the sloth, still clinging to Fox’s neck, bit the vulture, attacking the joint that held its wing to its body. The bird’s hold slackened for a second and Fox seized her chance to wriggle free. She sprang up, blundering on, ducking and sidestepping when the next vulture hurtled down towards her.

The swamp seemed to go on forever and Fox could feel tears burning behind her eyes. She was tired now. She couldn’t outrun the harpy and she knew it. Morg had dark magic on her side and sooner or later she’d close in.

Heckle flapped on, puffing hard. ‘Heckle wants the girl to know she won’t leave her. And nor will Fibber.’

The sloth leant against Fox’s cheek, then squeezed her hard, and Fox tried not to let her tears fall. She made one last attempt to focus on escaping, despite knowing that this was where her quest ended. Where everything ended. With no one to stop her, Morg would find the Forever Fern, and then the Unmapped Kingdoms and the Faraway would crumble. And yet still Fox kept running because sometimes the very last thing to leave you is hope.

Then Fox felt a cold and leathery hand thump down on her neck and she felt even that tiny kernel of hope shrivel.

‘Silly girl.’ The harpy’s breath was a rasp. ‘You really thought that someone as pitiful as you could find the Forever Fern and save the world? You actually believed that you could make a difference?’

Morg stood upright now, towering over Fox like a giant bat, while Heckle twisted away from the vultures massing round her in the sky.

Fox stopped struggling and sobbed in fear.

‘Look at you,’ Morg spat. ‘Worlds are built by people of power, not by insignificant little girls.’

The words may have been spoken by a harpy, but they made Fox think of her parents and the things she had been told her whole life: that stamping on others and being more powerful than everyone else was the only way to get to the top. And, now that all seemed lost, Fox wondered whether they’d been right. Perhaps being kind and helping others only ever led to being trampled on. Maybe hearts were safest if shut behind very high walls.

Then the sloth on her back nuzzled his head against Fox. And the warmth of that gesture, the affection bound up in it, made her realise that, despite how everything had panned out, her parents and Morg were wrong. Fox would have traded all the money in the world, and all the power that came with it, to have even the smallest of chances to save the Unmapped Kingdoms and the Faraway – and to love and be loved by her brother.

The harpy kept her hold on Fox, opening her wings wide to perform a curse that would snuff the light out of the Faraway child in an instant. Fox quivered as Morg threw back her head and laughed. Then black smoke hissed out from her wings.

But, at the very moment the smoke was about to seep inside Fox’s mouth and snatch her life clean away, something large and strong barrelled into the harpy and knocked her to the ground.

For a second, Fox wondered whether Total Shambles had come back. But what she saw on twisting round was not a swiftwing.

It was a panther, with a roar that rattled the leaves on the trees and fur that was unmistakably gold.