As Cordelia and the pirates made their way up the gully, climbing a spine that was thousands of years old, Cordelia noticed more and more plants and animals, insects and birds that she had never seen before.

She imagined the slow congregation of endangered species arriving at this island over the past thousand years: from plant and animal kingdoms alike, seeking refuge on the bones of an ancient creature. She pictured seeds floating through the night; birds drawn across the sky, following the purple wink of the star like thread following a needle. She imagined trees, the marrow of their wood humming with desire to be safe from the bite of the axe; and the urgent flick of insect wings in the starlight as they flitted for safety.

All had come here for sanctuary.

Cordelia ran her hands over rough tree trunks and smooth rocks, stroked strange flower petals and the iridescent shells of beetles, and she realized she had been wrong about the island. When she’d first arrived, she had felt violent magic all around her. The place had been an assault on her sensitive magical senses.

Now she understood: there had been so many new magical things crowding in on her that she’d been overwhelmed, like listening to seven thousand symphonies at once.

She tuned her ear to the quiet music of a single flower. It sang its magic, a tender song of hope in darkness.

‘Those flowers glow at night,’ Never said, watching her as she cupped the blossom gently in her hand. ‘D’you know what they’re called?’

Cordelia shook her head.

‘I don’t know their name,’ she said. ‘But I can tell they’re very precious.’

Further up the gully, on what Annie proudly told Cordelia was a prehistoric leg bone, they found Billy Bones and Vinegar Jim racing tumbling shrubs along the high white rock, speeding close to the edge and roaring with laughter.

‘Come down!’ Tabitha yelled. ‘We’re showing our teacher the island!’

As Billy and Jim clambered down from the leg bone, Cordelia watched several snails with orange shells the size of carriage wheels inch slowly upwards past them, leaving bright trails.

‘D’you know what tree that is?’ Annie asked, pointing up to a majestic tree taller than a cathedral spire, with branches like wide-open arms and bright green, heart-shaped leaves.

Cordelia did not recognize the leaves or the bark, but she carefully laid her hands on the tree trunk. Hope surged through her palms with the sonorous power of whale song.

She did recognize this magic! But it was like recognizing a song she’d once heard somebody humming, except now it was being played by a full orchestra.

Cordelia remembered – when she was very small, one quiet afternoon in the Alchemy Parlour – her Great-aunt Petronella unwinding her silver hair and handing Cordelia her ancient wooden hatpin. As her hand closed over it, Cordelia had felt a thread of faint hope humming in her hand.

‘This is made from a branch of the last Soulhope Tree,’ Great-aunt Petronella had told her. ‘When I was a young girl, that last Soulhope Tree was felled in the Ashdown Forest: the king had it cut down for his warship. On hearing this terrible news, my father went to try to save some seeds from the fallen tree. He begged the king for just one pod, but the king laughed at him and threw him a bare broken branch. My father turned that slim stick of Soulhope wood into a hatpin for me, because hope is the most important thing to keep in your head. Soulhope Trees could grow higher than any tree in the world, because they had the deepest roots. They should never be cut down or burned. When the king’s warship caught fire in the channel, his men despaired, and that is how the war was lost.’

Cordelia pressed her forehead to the vast trunk, thinking of her great-aunt, and whispered, ‘There is one still living. If I ever get home, I’ll have to tell her.’

She turned from the tree, wiping hopeful tears from her eyes, to find the pirates looking at her curiously.

‘It’s a Soulhope Tree,’ she sniffed, smiling. ‘Your island is extremely magical.’

‘It’s not our island,’ Jim corrected her. ‘It doesn’t belong to us; we belong to it.’

Before Cordelia could quite grasp this logic, the pirates pulled her through a narrow tunnel in the bone-rock to emerge in a wide forest glade that appeared to be draped with giant lace tablecloths. The tablecloths were each as wide as a galleon’s sails, swagged above her head. They hung in intricate patterns from all the trees, with frilly white rosettes in their centres.

‘This is Tablecloth Glade,’ Tabitha announced.

With a jolt in her belly, Cordelia realized that the white rosettes in the middles of the huge tablecloths were spiders. And the tablecloths were, in fact, enormous spiderwebs.

Cordelia staggered backwards as a spider the size of a dinner plate descended silently on a thread of web, to peer at her with eight eyes.

‘They won’t hurt you,’ Never told her. ‘The worst they’ll do is try to decorate you.’

He indicated Billy, who giggled and wriggled as a white spider spun an elaborate silken cape around his shoulders.

Cordelia studied the creature as it worked. Its legs were covered in snowy hairs and its eight bright eyes frilled with corkscrew ringlets. It was somehow neat and flamboyant at the same time, its legs busy and clever, its movements quick and trim.

They found Smokestack sitting on a boulder halfway up the glade. His grey hair had been embellished with an ornate hat made entirely of spider silk.

‘Thought we’d find you here, Smokestack!’ Tabitha called.

‘I just love to sit here and watch them spin,’ he said with a contented sigh. ‘They make yarns of such beauty; I don’t know how I could ever spin a yarn to match theirs.’

‘Maybe our teacher will teach you?’ Jim suggested.

But the teacher in question hardly heard this suggestion. Cordelia watched as Shelly carefully laid some frilly flowers on a rock. Several spiders scuttled enthusiastically down from their webs and began eating the dripping nectar.

Cordelia was reminded of her father. He always gave thank-you gifts to nature when collecting ingredients and never took more than was needed. Prospero Hatmaker believed that nature deserved the utmost gentleness and respect. Rivers should always be called by name, clouds should be bowed to (whatever mood they were in), birds should be addressed Sir or My Lady, and even trails of ants snaking across pavements should be given right of way.

He would love this island, Cordelia thought. Every leaf and petal contained enchantment, every bird call was a song of wonder, every insect a living glyph of mystery. Every breath of air carried magic on it.

‘We should show her the lagoon,’ whispered Annie.

With sudden enthusiastic howls of ‘LAGOON!’ the Troublemakers surged away up the white-veiled glade.

The lagoon was a deep, still pool surrounded by flowers that glowed like fallen stars. A waterfall tumbled down over smooth white vertebrate rocks at one end. Huge lilac boulders lay half submerged and vines trailed into the water, which was so clear Cordelia could see the bottom, shining brightly.

‘It’s solid silver down there. We think it’s from centuries of moonlight falling on the ancient Sea Dragon’s pelvis bones,’ Never said. ‘We call it Moonstruck Lagoon.’

The Troublemakers had already shed most of their clothes and were huddled together holding a whispered conference in the shallows. Shelly nudged the others as Cordelia approached. They turned, smiling shiftily, all looking rather absurd in their underclothes and enormous barnacled hats.

‘Why don’t you take your hats off?’ Cordelia asked.

The wildness in her wits was telling her something was wrong.

Then, out of the corner of her eye, she saw a figure flash through the trees above the waterfall.

It was a girl, running fast.

This was no pirate; this person was too small. It must be –

‘PRUDENCE!’ Cordelia yelled.

Startled eyes flashed before the girl turned and fled.

Without even removing her boots, Cordelia dived into the lagoon, taking the most direct route in pursuit.

Never dived after her but she was too quick for him.

She splashed through the water, pirates bellowing at her to stop, and scrambled up the knobbly stones of the waterfall.

‘Prudence!’ she panted. ‘Wait! I’m a friend! Wait!’

At the top, she sloshed along the shallow river to find footprints – child-sized ones – that led through the deep mud of the opposite bank, into the glade beyond.

She could hear crashing in the jungle ahead of her. She shouldered her way through dense shrubs and pushed aside curtains of vines.

‘Prudence!’

Cordelia stumbled into a small glade and skidded to a stop.

Thorn Lawless stood in the yawning mouth of a cave, on the verge of being swallowed whole by the darkness. The pirate queen wore a mean grin.

‘She’s in there, isn’t she!’ Cordelia panted. ‘You’re keeping her in that cave! Prudence!’

Thorn hurled a sharp laugh at Cordelia, like a knife. ‘You want to look for Prudence in the Belly? Go ahead!’

Thorn stood aside and Cordelia was suddenly wary. This was too easy – the way some traps are too easy.

She walked slowly towards the yawning mouth and saw that the cave had once been the hollow ribcage of the prehistoric Sea Dragon. The huge struts of its ribs, arching above her, were overgrown with vines. The dripping deep-green air smelled of ancient secrets and primordial time.

Cordelia stood on the threshold, poised between the light and the dark.

‘Prudence?’ she whispered.

The only answer was a soft snicker from Thorn.

Cordelia stepped into the underworld.

As her eyes grew accustomed to the dark, she began to see wonders in it.

Crystals in the cave glowed; stalagmites like galaxies stretched up from the floor. Luminous rocks bulged on the ceiling like planets blooming in a night sky. It was extraordinarily strange and beautiful.

But she couldn’t get distracted. That was what Thorn wanted. Where had Prudence gone?

Cordelia noticed the tingle in her fingertips. There was something powerfully magic close by; she could feel it throbbing in the still air. It was something troubled and heavy – jagged enough to cut herself on – just out of reach.

She looked over her shoulder at Thorn, whose eyes flashed, daring her to brave it, to venture further in.

Suddenly a thought struck Cordelia.

In fact, her fingers knew before her brain did.

She took three quick steps, reached up and knocked the pirate queen’s hat off.