Eska shook her head. ‘You don’t know the Ice Queen like I do. We won’t stand a chance now she knows I’m free!’

Pebble slid further into Flint’s hood as if he could sense that he was largely to blame for this turn of events while Flint’s gaze faltered between the arch he had come through and the door leading on into the heart of Winterfang. He stormed across the hall towards the latter, leaving Eska trembling beside the music box. But, as Flint approached the doorway, the silver branches closed over the frame, barring his way on into the palace. And then footsteps sounded from a passageway beyond the door: heels clacking closer, followed by the slow swish of a gown. The stories of the Ice Queen swirled inside him.

She wears a dress made from the frozen tears of her prisoners. She can hex animals under her control with one strike of her staff. She can turn children to ice . . .

Flint thought of the inventions he had packed into his rucksack: his Camouflage Cape, made from the fur of snow hares, then washed in a casket of sunbeams. And his bone-handled Anything Knife, with a turquoise river gem slotted into the handle.

But these inventions had been made to help Flint slip through the passageways unseen, not to fight the Ice Queen, and with an aching heart he realised his rescue mission now lay in tatters at his feet. He raced back towards the arches. Panes of black ice were sliding across them, closing the hall in, window by window. The palace darkened as the moonlight was shut out, but Flint sped on towards the three arches still left open and, grabbing the key from the music box, Eska stumbled after him.

‘You are not coming with us!’ Flint cried as he hoisted himself into the biggest arch and hauled the rope from his rucksack. ‘You’ve already ruined my chances of freeing my ma!’

The footsteps beyond the hall grew louder and the flames began to hiss. Flint flung his barbed rope into the wall then glanced towards the tundra. The guards didn’t seem to be out there any longer – perhaps they were inside the palace now, having summoned the Ice Queen about the strange whistle sounding over the ice – and Flint knew that he only had a few seconds to make this escape work. The black ice burst out from the side of the arch and Flint gripped the rope and began to abseil down the palace wall.

But Eska wasn’t giving up. She clambered on to the arch in the nick of time, her body juddering from the cold, and Flint watched, aghast, as she grabbed hold of the rope above him as the last of the windows sealed shut behind her.

Flint slipped to the ground, barely using his mittens or his boots to grip the rope this time, and, moments later, Eska clattered down after him, her hands and feet raw from the rope. Then there was an almighty crash as the largest pane of black glass smashed apart.

Flint dragged Eska beneath the bridge. He couldn’t leave her now – she’d only give his presence away – and yet his mission was careering sideways. He hauled a bundle of clothes from his rucksack: a pair of sealskin boots and mittens and a parka and trousers made from grizzly-bear furs, and tossed them to Eska.

‘They were for my ma,’ he growled. ‘But you’ll need them if we’re going to make it out of this alive.’ He drew out a large and very soft white blanket next. The Camouflage Cape. ‘I didn’t need this on the way here because no one knew I was coming, but now thanks to you . . .’ He shook his head. ‘We need to run – fast – beneath the cliffs and if we stay under this cape we’ve a chance of making it unseen.’

Flint jumped as a high-pitched cry pierced the night.

‘Eskaaaaaaaaaaaaaaa!’

The voice was sharp and shrill and it swarmed over the Driftlands. Flint slid a look up to the palace to see a woman standing in the tallest arch, a crown of snowflakes glinting on her head. His insides clenched. The Ice Queen’s teardrop gown fluttered in the wind and beside the staff she held sat a wolverine, its dark fur a stain against the ice.

Flint turned to Eska, tucking her beneath the Camouflage Cape with him. ‘Run,’ he whispered. ‘Now.’

And, with the sound of the Tusk guards marching out across the bridge and the Ice Queen’s screech echoing across the kingdom, the two children darted out.

They kept to the cliffs, their boots pounding against the ice, their breath pent up inside them, and, though Eska was unstable on her feet, Flint propped her up and they ran on towards the cavern where the huskies waited.

Flint yanked Eska inside the opening in the cliff and the dogs clustered round them, warm and loyal and ready for the homeward journey.

Eska leant against the wall. ‘Free from Winterfang,’ she panted in disbelief. ‘Free at last . . .’ The Ice Queen’s voice tore across the ice again and Eska edged further inside the cavern.

‘Stand on the metal brake between the runners while I attach the dogs,’ Flint muttered. ‘I don’t want them whisking the sled away before we’re ready to go.’

Eska hurried over and pressed down with her boot, but, after the Ice Queen’s enchantment, her body was no match for the spirited dogs. The brake flung up, the sled jerked forward and Eska stumbled over. But Flint was on it in a second, slamming a hand on to the side of the sled until it stopped.

Eska picked herself up and wedged a foot down over the metal again, as hard as she could. ‘That cape,’ she whispered, nervously placing her other boot on to the brake to stop it edging forward, ‘we never would have escaped without it. And it was made using magic, wasn’t it? That’s the reason we got away . . .’

For a second, Flint’s shoulders squared with pride – it was the first time anyone had congratulated him on an invention or even been vaguely interested in Erkenwald’s magic since the Tusk Chief’s death – but then he remembered himself and scowled.

‘Shut up and listen to me.’

He stamped his boot over Eska’s so that it sank deep into the snow and the sled held firm.

‘The cavern widens into a tunnel and when it comes up on the tundra we’ll be a safe distance away from the palace. The guards might see the huskies, but if we and the sled are tucked under the cape they’ll just look like a pack of wolves running from that distance, and, with any luck, we’ll make it to Deeproots without being tailed.’

Eska nodded.

‘We must be quick though – we need to get as far as we can while the night hides us.’

Eska nodded again then, avoiding Flint’s eyes, she whispered, ‘What’s Deeproots?’

‘What’s Deeproots?’ Flint scoffed as he untangled the ropes that tied the dogs to his sled. ‘Only the biggest forest in the kingdom and home to the legendary Fur Tribe. Everyone in Erkenwald knows that.’

‘Everyone except me,’ Eska mumbled. A spot of colour had returned to her cheeks, but the clothes she wore swamped her body and she looked pitifully frail inside them. ‘Will I be safe with your tribe?’

Flint looked up. ‘You can’t just wander in and join our tribe! There are rules, you know.’

‘But . . .’ Eska’s voice trailed off. ‘I’d be an extra pair of hands about the place. I’d help.’

‘It doesn’t work like that,’ Flint said. ‘You have to be one of us from the start.’ He tossed his rucksack on to the fur-lined sled. ‘Once we’re in Deeproots, you’re on your own. I don’t know who you are, what tribe you’re from or why the Ice Queen thinks your voice is so important, but I just missed my chance of freeing my ma because of you. The only reason I’m not leaving you here is because I don’t trust you not to blab about my whereabouts to the Ice Queen.’

Pebble yapped from Flint’s hood.

‘And because Pebble is playing up.’

Pebble growled.

Flint sighed. ‘And I suppose because you might know things that could help us fight the Ice Queen.’

Satisfied now, Pebble settled into Flint’s hood.

Flint shoved Eska off the brake, pushed his own foot down on it and glowered at the ball of white fur curled up in his hood. ‘I blame you entirely for this detour, Pebble. You’re going to have some serious explaining to do when we see Tomkin.’

Pebble pretended to snore and Flint rolled his eyes, but, when the wolverine’s growl juddered across the sea outside, he pointed to the sled.

‘Sit down on the furs in front.’ Flint lifted the Camouflage Cape over his shoulders. ‘And hold the end of the cape up a little so that I can see out ahead of us.’ He paused. ‘But don’t expect any conversations. It’s hard to steer a sled, be cross and talk all at the same time.’

‘Can – can I just ask your name?’ Eska stammered.

Flint scowled. ‘Why do you need it?’

Eska blinked. ‘In case we do decide to have more conversations.’

‘It’s Flint.’ There was a pause. ‘And we won’t be having any more conversations for a while.’

Eska nodded meekly, then Flint lifted his foot from the brake and, as the dogs hastened into the tunnel, the wolverine’s growl petered out into silence.