Moll woke to someone tugging at her coat sleeve and for a second she imagined she was back in her wagon in Tanglefern Forest and that Mooshie had come to get her up for morning chores. Then her eyes flicked open to see Gryff pulling at her cuff with his teeth and the beech roots curved over her head.

The forest was already awake: a woodpecker drummed at a nearby tree and a red squirrel scampered along the path. It was a cold grey morning and even beneath the shelter of the roots Moll’s feet were numb inside her boots. She dug a hand inside her coat pocket and, on feeling the very slight weight of the piano string against her fingertips, she leant over to tickle Gryff’s throat.

His greeting call rumbled in her ears. ‘Brrroooooo.’

At the sound, Siddy opened his eyes and yawned.

‘We need to head on and find Aira,’ Moll whispered. ‘We shouldn’t stay in this forest any longer than we need to.’

Gryff slipped out from the roots to hunt for food while Moll shook the last of the nuts and berries from the satchel and Siddy stooped to pick a handful of wood sorrel growing by the path. Then they followed the wildcat along the path above the river. Once or twice they saw the forest stir – a greenfinch flitting between branches, a roe deer picking its way through the ferns – but otherwise the place was quiet, a woodland scarred by the Shadowmasks’ magic.

Eventually the oak, ash and beech trees thinned and the path dropped level with the river. The water ran more slowly here and Moll watched the reflection of overhanging branches break apart as a small fish jumped and a dipper bobbed down from a rock to follow it. They walked on, right out of the trees, and there, rolling across the landscape for as far as they could see, were the moors. Where one hill sloped down another rose up, a sprawling wilderness purpled by frosted heather.

Siddy stopped for a moment. ‘The Rambling Moors.’

Moll blinked, unable to find words large enough to describe the emptiness before her. She’d been out on the heath beyond Tanglefern Forest many times with Domino – she’d raced into the open where the wild ponies roamed and relished the freedom of space – and somehow she’d imagined the landscape here to be like that. But Moll’s thoughts hadn’t been big enough to hold in what the moorland was. It didn’t rise up into towering mountains; it didn’t need to. The hills owned the landscape just by being there. Grazing sheep were reduced to white dots, streams shrank to wrinkles and the path ahead of them was almost lost amid the heather. The moors swallowed everything and, facing them now, Moll gulped.

‘How are we going to find a feather from burning wings out here?’ she said.

Gryff stalked along the path, out on to the moors.

Siddy straightened his flat cap. ‘By following him. By putting one foot in front of the other until we find Aira MacDuff and that bothy.’

Moll watched the wildcat’s shoulders rise and fall, his paws silent on the rocky track, and she felt stronger somehow, and, with Siddy by her side, she followed. The river quietened into a stream and ran west, away from them, but they continued on the path as it wound on to the moors. Moll could see the distant hills were scattered with snow and from the hollows a mist was rising – but she had darker things than the weather on her mind. Out here on the open moors, she was easy prey for the Shadowmasks . . .

A covey of grouse sprang from the heather and Moll jumped as Gryff tore off after them. Her eyes widened as the wildcat bounded further and further away, then the birds flew out of his reach and he sloped back to join the others. Moll ran a hand over his back because, for a fleeting second, it had felt as if he might keep running into the wilderness without her. Here on the Rambling Moors she could feel a different kind of freedom rising from him, a slice of the wild only matched by the landscape around them. This, a small voice within her said, this is where he really belongs.

It was after they’d been walking for an hour that they clambered over a gate set within a fence and Siddy noticed the highland cow – a lone male grazing further down the hill.

He looked at it longingly. ‘Just think what we could do with a highland cow at our side. He could carry our bows and supplies and we could ride him when we got tired.’

Moll glanced at the cow’s horns. ‘It wouldn’t end happily, Sid.’ She paused. ‘Once all this is over, I’ll go hunting for a pet with you – something a bit bigger than Hermit, perhaps, and a bit less slimy than Porridge the Second.’ She nodded down the path. ‘Right now though we’ve got to keep going.’

‘Can’t we just rest for a moment?’ Siddy asked.

Moll shook her head. ‘We haven’t got time.’

They walked on and, while Moll hastened to keep up with Gryff, Siddy began to lag behind, whistling every now and again to try and attract the attention of the other highland cows they passed.

‘Come on, Sid!’ Moll called without looking back.

She knew Sid was tired and sore after the climb into the gorge the night before and that he was missing Porridge and Hermit, but worrying about all that wouldn’t help them now. Moll tried to ignore the ache in her own legs and focus on placing one foot in front of the other, and it was only when she looked up that she noticed how much the weather had closed in. Great bands of mist hung where the moors ahead had been and all around her tendrils of fog crept closer. Moll watched as the mist inched over the heather like a living thing. She spun round to look for Siddy, but the path behind her was empty.

‘Sid!’ she called. ‘Where are you?’

She waited a few moments, but nobody emerged through the haze. Insides turning, she careered back down the track with Gryff.

‘Sid!’ she cried. ‘Sid!’

She rounded the bend in the track to where she assumed her friend would be, but there was only a screen of mist.

‘Sid!’ Moll shouted again.

Her voice echoed across the moor, caught in the hanging fog, but Siddy didn’t reply. Moll stumbled into the heather with Gryff and ran blindly, her face wet with sweat. She’d been impatient again, and charged off, even though she knew Siddy was tired and had only wanted a little rest.

Moll turned blindly, this way and that. ‘Sid!’ she called. ‘Sid!’

Gryff brushed against her legs, but whichever way she turned Siddy was nowhere to be seen. Moll’s mind whirred with images of her friend at the bottom of a ravine, of him gored by a highland cow or, worse, snatched by a Shadowmask. She blundered on, shouting his name.

The path had vanished and Moll could barely see Gryff’s black-and-white stripes, even though he was just by her side. And then suddenly the ground gave way beneath Moll and she fell forward, landing with a slap on something soft and muddy.

‘No,’ she breathed, panic rising in her throat as she remembered Domino’s words on the train – of peat bogs that could suck you down whole . . .

Frantically, she reached out her arms towards Gryff, but the peat sucked hard, dragging her feet then her legs and then her waist into the cold, wet earth.

‘Help!’ she yelled as Gryff clawed at her coat.

Then Moll’s eyes widened as two shadowy hands in the depths of the bog wrapped round her shins before heaving at her legs and forcing her down. Moll heard Gryff growl as he tried to pull her from the creature, but whatever was lurking in the bog wasn’t letting go. Its hands clamped tighter round Moll’s legs and little by little she felt her body slip from Gryff’s hold until the mud was slopping around her neck.

‘No!’ she gasped, her lungs snatching at the air. ‘No!’

Moll’s eyes locked on to Gryff’s as the mud rose above her chin. She sealed her lips tight, forcing the breath out through her nose, then there was a loud belch as her whole face was wrenched beneath the surface. The earth closed round Moll and she thought of Siddy out on the moor without her, of Gryff struggling above the surface and of the Shadowmasks waiting to conjure their eternal night.

She bucked and twisted, but the hands kept pulling and Moll felt her mind shutting down and her limbs growing weak as she was hauled deeper and deeper into the blackness of the bog.