Jamming her poles into the snow, Eska led the way round the side of the mountain.

‘Ski! Fast!’ she cried.

Down they went, undoing hours of hard climbing, but that didn’t matter now because Needlespin was scuttling closer, wielding a silver-spiked ball and chain, and, though Balapan dived at him again and again, he barged her out of the way – and stormed on.

‘Visitors?’ he cackled. ‘Running away so soon?’

His voice was full of spiked edges and at the end of every sentence the words snapped off like broken ice.

Eska turned panicked eyes to Flint.

‘Keep going!’ she shouted. ‘Keep going!’

But Needlespin was gaining on them, closing the children in between two mountains. Eska scanned the slopes for a crossing point until her eyes rested on a fallen boulder covered in snow that was wedged between the mountains.

She took in the vast drop below it – several hundred metres, at least – then she found herself pointing towards the boulder with her ski pole. It was the only way.

‘Across there!’ she bellowed, nipping from the mountainside on to the boulder.

Blu followed with Flint close behind.

‘You think I won’t leave my mountain?’ Needlespin screeched.

And he leapt over the gap between the slopes as if he was jumping over a puddle. He landed in a crouch and his icicled limbs creaked. Then he looked up, his teeth jangling. ‘Not when I’ve been given orders by the Ice Queen to hold you here.’

Eska’s mind whirled as they skied on down the next mountain. She thought about the inventions stashed inside Flint’s rucksack and the quiver on her own back, but there was no time to reach for anything like that because Needlespin was now swinging the ball and chain above his head.

‘Ice!’ he shrieked, thumping the spiked ball down into the snow. ‘More ice!’

And Blu, Flint and Eska screamed because, beneath their skis, they felt the mountain harden into a slope of bruised ice. Their skis lost grip, their poles clattered against the surface and, like three runaway marbles, they shot down the mountain.

Balapan plummeted, too, but she was thinking faster, seeing faster, bending the wind to suit her own purpose and missing the treetops and jutting overhangs by the slightest turn of her feathers. The eagle called out above a lip of ice.

Eska summoned up her voice until it was as loud as she could make it. ‘Point your skis towards Balapan!’

‘That’s a jump!’ Flint screamed. ‘We’ll soar for miles! Blu won’t manage the landing!’

But Eska was tilting her skis towards the eagle now, towards the mound of glittering ice scooping up to the next mountain, and, with no better ideas, Flint snatched Blu’s hand and steered his little sister after Eska. Pebble’s eyes grew large as they neared the lip.

And, close on their heels, Needlespin sniggered. ‘You can’t outrun me, children! Wherever you go, I’ll find you!’

His words echoed through the Never Cliffs, but Eska, Flint and Blu careered on and then – one, two, three – they were soaring off the ice lip, climbing the height of the mountain opposite, in the air.

They landed with a poof in powder snow, a tangle of skis, poles and limbs, before a cluster of trees dripping with icicles.

Flint twisted round to face Blu. ‘Are you okay?’

Blu’s bottom lip was wobbling. ‘I scared, Flint. Scared.’

Eska glanced around. ‘I think we’ve lost Needlespin . . . Maybe he could only cross those first few mountains?’

Pebble scrambled out of Flint’s coat and peered closer at a tree behind them. He took a few steps forward and the silence throbbed. Then, as Balapan veered towards them, Eska spotted a movement within the trees. A silver-blue eye flicked open between the branches, an icicled claw curled round a trunk and then, as Pebble clattered back towards Flint, Needlespin burst out from behind a tree.

‘Did you miss me?’ the monster spat.

He lumbered towards them and the group scrambled to their feet and launched their skis down the mountain. But they could hear Needlespin’s ball and chain whirring in circles and as it spun above him a torrent of icicles shot out from the silver spikes, narrowly missing the children’s furs.

‘Ice spears!’ Blu cried.

Flint clutched her hand for a moment. ‘Keep going! Just keep going!’

But Eska had learnt to listen when the panic crowded in – to eagles, to the wild and to the quiet beat of her heart. Whitefur, it was saying. Remember what Whitefur said to you back in the Giant’s Beard. And, as she darted between trees and swerved round humps and dips in the snow, she thought of her hideaway behind the waterfall and how a man who might or might not have been an Erkenbear had filled it with Diamond Dust.

‘Whitefur,’ she whispered. ‘Whitefur.’

Flint shot her a glance as he stooped beneath a branch. ‘What?’

‘Whitefur,’ Eska said again as one of Needlespin’s icicles whizzed past her ear. ‘At the time when you need help most, say my name – that’s what Whitefur said!’

And as Needlespin roared behind them, his teeth jangling like hollow bones, Flint and Eska shouted Whitefur’s name. Again and again they bellowed it and at first Needlespin simply laughed and hurled out another batch of icicles.

Then a curious thing happened. Tiny flecks of shimmering silver puffed out into the air around Flint and Eska and no matter how many times Needlespin pitched his weapons he couldn’t hit the boy or the girl. The icicles simply bounced off the shell of sparkling snow and clattered to the ground.

‘Whitefur’s Diamond Dust,’ Eska breathed. ‘It’s protecting us!’

Then she watched, aghast, as Needlespin charged down the mountain behind them and tossed a spear at Blu. It struck her on the elbow and she cried out in pain. Flint swerved towards her, taking a little of her weight.

‘Say Whitefur’s name, Blu. It will help you!’

Blu leant into her brother’s side as they skied. ‘Don’t understand. Don’t understand.’

‘Yes, you do, Blu. You do. Trust me. Say Whitefur’s name.’

‘White – Whitefur,’ she stammered.

‘Yes, Blu! Again – louder this time.’

Blu flung the Erkenbear’s name out into the Never Cliffs as Needlespin’s spear careered towards her. ‘Whitefur! Whitefur! Whitefur!’

The icicle crashed to the ground and all around her the Diamond Dust danced. Blu, Flint and Eska flew on down the mountain, shooting off bumps and veering round trees.

‘Now what?’ Flint shouted to Eska.

‘Follow Balapan.’

And though Needlespin scuttled over the snow towards them, flinging his ball and chain against the trees, they followed the eagle – until it circled a cliff edge with a terrifying drop beneath. Flint turned to Eska as they raced towards it.

‘No,’ he breathed.

Balapan plummeted down and then tucked her wings in just before she hit the snow. She soared up into the sky again and, with one eye on the snow and one eye on her eagle, Eska tried to understand what Balapan was saying.

‘Pull up at the last minute,’ she panted, tucking into a ball to quicken her pace. ‘And grab whatever you can to stop yourself from falling. Trust me!’

Behind them, Needlespin’s voice hacked through the air. ‘Over you go! Splinter splat! You’ll be easier to guard with broken bones.’

Eska, Flint and Blu were level now and, as they sailed towards the cliff edge with Needlespin just metres behind, they yanked their weight sideways, slipped off the edge and then clung to the tops of the trees immediately beneath.

Needlespin charged over the lip, his arms wide, ready to crush the children in his icy grasp, but they were nowhere to be seen. And as the monster leapt into the air he realised his stride had been too big – too greedy – because he’d overshot his prey and the trees they clung to and far, far below, snaking through the cliffs, was the one thing that could break him.

Black ice.

The frozen river loomed like a shadow and Needlespin picked up more and more speed as he hurtled towards it, limbs flailing. Then there was an almighty crash as he hit the ice and Eska, Flint and Blu, clutching at the branches of the trees beneath the ledge, watched the broken pieces of Needlespin’s body rattle across the river.