They crossed the river over a bridge made of bones and Fox held her breath the whole way, partly because she was terrified one of the bones was going to fall away and she’d plunge into the black water and partly because she was dreading the Midnights hearing the bridge creak as the group made their way across.

But the monkeys didn’t hear or see the intruders approach because Heckle had stayed true to her word. The parrot had flown, unseen, across the river a short while before the others and then, hidden in the undergrowth around the avenue, she had crept behind the trees until she was beyond the Midnights. Then she had squawked loudly. And, at the exact moment the monkeys craned their necks towards the disturbance, Fox and Deepglint, together with the sloth, had made their way over the bridge.

Heckle skulked back through the cover of the undergrowth to join the others who were crouching in the reeds before the avenue of trees. The ticking sound was louder now they’d crossed the river and as Fox watched the Midnights, their orange eyes gleaming in the trees, she hoped that her hunch about them was right. Because, if it wasn’t, this was the beginning of the end.

The group watched and waited, just as they’d said they would, and then, as dusk gave way to night and a full moon rose above the trees, Heckle hopped onto Fox’s shoulder and Fox drew the doubleskin mirror from her pocket. She held it up to the china-white avenue of trees and the undergrowth around them. Then, under the moonlight, she looked at her reflection and gasped. Her skin was the same shadowy green as the reeds around them. She, and indeed the sloth around her neck and Heckle on her shoulder, were completely camouflaged by their surroundings.

Now it was Deepglint’s time to act. He dipped his head at Fox, as if to wish her luck, then he stood up, stalked into the avenue of trees – and roared.

The Midnights, caught off guard, shrieked in surprise. Then they began jumping up and down on the branches, hissing and squealing with excitement. But they didn’t leap down to attack the Lofty Husk because, beyond the bone walls, the panther’s roar had summoned another.

Moments later, the gate to Shadowfall creaked open and the Midnights yelped with pleasure as a giant ape swaggered on two legs between the trees. Fox baulked as she took in the long, swinging arms that ended in clawed fists, and the glinting eyes – fixed on the Lofty Husk – that sat above a mouth filled with daggered teeth. Hanging round the ape’s neck, on a piece of string, was the object Deepglint had spoken of earlier, the object Fox’s whole plan hinged on tonight: a key.

Heckle shrank into Fox’s hair at the sight of the ape and the sloth on her back stiffened. Before them was a being capable of stealing a Lofty Husk’s magic.

The panther roared again as the ape drew up in front of him. And Fox knew that if she didn’t act now she never would. So, still camouflaged and therefore unseen by the Midnights and Screech and even by Deepglint, Fox shot out of the undergrowth and raced between the trees. She ran past Deepglint, her skin, hair and clothes the white of the trees one second and the colour of night the next. The Lofty Husk only knew Fox had passed him and that their plan was on track so he should stand his ground because the sloth had reached out a paw in the nick of time and brushed it against the panther’s fur. Fox took a wider berth round Screech before climbing onto the lowest branch of the tree behind the ape.

‘You come again, cat!’ Screech threw back his head and laughed. ‘Did you not learn from last time that your magic is nothing in the face of Morg’s? That you—’

He stopped suddenly and wheeled round. Fox froze. The ape must have heard Heckle use her beak to snap off a boned twig a few branches above her. Was their plan foiled then? Had they wasted the magic of the doubleskin mirror? But Screech looked right through Heckle, Fox and the sloth as he scanned the branches.

As soon as the ape turned back to Deepglint, the plan was back in action and Heckle passed the twig to the sloth on the branch below, who then slipped down several branches at once and passed it to Fox. Then, as quickly and as silently as she could, which was difficult because of the increasingly cumbersome satchel on her back, Fox slithered to the end of the branch. Holding her breath, she stretched out her hand with the twig clasped in it.

The ape towered above Deepglint, his clawed fists raised, and the Midnights in the trees barked with delight.

Fox reached out the twig towards Screech, trying to steady her shaking hand. She focused intently, blocking out the ticking noise droning from the trees and the hollering of the giant ape. All her attention was on moving the twig towards the string around Screech’s neck. Finally, she managed to scoop the twig under the string. Then she yanked hard.

The string and the key flew up into the air and Fox flung her arm out to catch them. For one fearful moment, it looked like the key would slip through her fingers, but then she felt it firm in her hand. Her fist curled round the metal and the ticking noise that had filled the trees suddenly stopped.

The monkeys – every single one – dropped from the branches they had been clinging to. As they fell, they began to twist and shrink until all that was left at the foot of the trees were dozens and dozens of mangled black clocks. Even Screech, a tower of brute strength and dark magic, now shuddered on all fours as his body began to dissolve into a pile of black grit.

Fox could hardly believe her eyes. Her hunch had been right: Morg’s Midnights weren’t ordinary monkeys. They were monkeys! Not animals made from flesh and bone, but clockwork creatures controlled by the cursed key Screech had worn around his neck. And that’s why the monkeys had kept coming for Jungledrop’s thunderberries, animals and Unmappers, even when injured: because every time they returned to the Bonelands Screech simply wound them back up again with his key. The only way to kill them was, as Fox had suspected, to steal the master key.

Fox wailed in the tree as Screech’s voice, the last part of his magic to depart, rose up from the pile of grit.

‘You will never enter Shadowfall,’ he sneered. ‘The way in looks just like the way out!’ He laughed darkly, then his voice grew fainter. ‘And you will never beat Morg. Her reign is only just beginning…’

The ape’s voice ebbed away until, finally, silence fell.

Fox pocketed the key, scooped up the sloth and, with Heckle fluttering excitedly round her, she scrambled down from the tree. Then she ran towards Deepglint. Her plan hadn’t turned out to be a total disaster! By working together, they had found a way past Morg’s guards.

‘We did it!’ Fox cried. ‘We actually did it!’

Deepglint smiled. ‘But of course we did. Because, when individuals come together, worlds can be shaken.’

Before Fox could stop herself, she’d flung her arms round the panther’s neck and hugged him. The Lofty Husk wrapped a large paw round her waist while the sloth burrowed under her chin and Heckle nestled into her hair. Fox had never been hugged before and now she was being held by a panther, a sloth and a parrot.

Fox had always assumed that hugging meant things moved about on the outside – arms round waists, heads on shoulders – but it also seemed to be about things shifting on the inside. Because hugging was an overlapping of hearts, too, and that, Fox concluded, was what made it so wonderful. Her eyes filled with tears suddenly and she felt very glad that she was still invisible. But, when the camouflage wore off a few seconds later and Fox appeared with blurry eyes, no one said anything about it. And Fox made a mental note that crying during a hug didn’t mean that everyone ran away from you afterwards.

The group eyed the gate between the bone walls. There was a ruined courtyard beyond. A fountain still stood in the middle, but the water had long since run dry and the stonework was covered in algae. There were statues here and there, but most were half crumbled to the ground and tangled in creepers.

‘We’d better get going,’ Heckle said, fluttering up from Fox’s shoulder. ‘Who knows what state Iggy could be in or what Morg’s really up to, but if the Forever Fern is inside Shadowfall we need to break in and find it before she does…’

Fox laid a hand on the gate. She had presumed it would hold fast, another obstacle steeped in curses to stand in their way, but it swung open, creaking eerily as it did so. Fox felt the sloth shudder on her back, then she and Deepglint walked inside.

Fox looked about her. There was something sad about the courtyard. The statues – carvings of swiftwings, boglets, trunklets and all manner of magical creatures – might once have been magnificent, but had now been left to decay. A temple reared up against the moon. Perhaps it had been grand before, but now it was draped in moss and much of the stonework had flaked away.

There were steps leading up to a door that was closed and barred with a mesh of vines so thick they looked like chains. This, it seemed, was the only way into the temple because there were no windows and the bone walls that enclosed Morg’s stronghold ran right up to the sides of the temple itself, so there was no space to creep round.

Fox picked her way between the statues until she was standing in front of the huge stone door. She tried pulling at the vines that criss-crossed it, and Heckle also tried clawing and pecking at them, but they clung on with supernatural strength. Even when Deepglint barged into the door with all his weight, it still didn’t open.

The Lofty Husk looked at Fox. ‘I fear we are going about this the wrong way. What was it Screech said just before he died?’

Fox shivered as she recalled his voice hanging between the trees. ‘The way in looks just like the way out.’

The parrot sighed. ‘Heckle is so confused! Of course a way in looks like a way out! A door is a door – you go in and out of it.’

‘We’re missing something then,’ Fox said. ‘We need to think about this completely differently.’

She turned away from the door, less sure now that the answer lay there, and began walking between the statues. She paused before the one just inside the gate. It was smothered by ivy and moss, but even so she could see that it was a unicorn. She felt the sloth shift position on her back and noticed he was craning his neck towards the statue.

Heckle landed at Fox’s feet, then cocked her head up at the sloth. ‘Fibber is thinking it strange that the whitegrump’s eyes are glowing.’

‘Whitegrump?’ Fox asked.

‘Jungledrop’s version of a unicorn,’ Deepglint explained. ‘Though decidedly worse tempered.’

Fox started to pull the ivy and moss from the head of the whitegrump so that she could get a better look. And, when she did, the group gasped.

‘Its eyes are mirrors,’ Deepglint murmured.

The mirrors were smudged with soil, but when Fox looked into one she could still see her reflection staring back and the gate to the courtyard behind her. ‘The way in looks just like the way out,’ she said quietly. ‘It makes sense now… Clever Fibber for noticing the whitegrump’s eyes.’

The sloth gave a bashful smile.

Deepglint frowned. ‘What are you and Fibber suggesting, Fox?’

‘This mirror reflects the gate – the way out,’ Fox replied excitedly. ‘So, what if the way in is somehow through the whitegrump?’

Hastily, Deepglint brushed the rest of the dirt and moss away from the mirrors, then Fox pressed down on them with her fingers. And, as she did so, there was a crunching sound, like stone gears slotting into place. Suddenly the statue of the whitegrump lurched backwards, like a horse rearing, and a way into Shadowfall opened before them.