‘What are we going to do? They’re looking for a girl in purple clothes with a reindeer.’ Bianca looked down at her jumper and her open coat in despair. ‘We’ll be caught immediately.’ She felt panicky. ‘We need a disguise.’

‘What is a disguise?’ Pordis tilted her head.

‘We need to make you look like something else. Something that isn’t a reindeer.’ Bianca looked hard at Pordis’s antlers. They were going to be difficult to hide.

‘I can walk on my hind legs like a human.’

‘You can?’

‘Yes,’ Pordis said proudly. ‘I can do seven steps before I fall over.’

‘Hmm, I don’t think that’s going to work.’ Bianca got to her feet, fastening her coat to hide her purple jumper. ‘Wait here. I’ll be back as soon as I can.’

Running to the spot where she had seen the snowman being built, Bianca called out to the children, ‘Can I help?’

‘We’re making a snowman parade,’ a tall boy replied, nodding eagerly, and pointed at five towers of snow. The snowman he was working on was wearing a yellow dressing gown.

‘Brilliant,’ Bianca said, grabbing a handful of snow and patting it into a gap on the nearest snowman’s body. ‘What are you going to dress the others in?’

‘Don’t know,’ he admitted with a shrug, and she guessed the dressing gown had been his.

‘There are loads of rugs and stuff over there.’ She pointed to the giant toadstools.

‘Ooh, that’s a good idea,’ said a girl in pink pyjamas who was rolling a ball of snow with a friend. ‘Come on.’ And the pair raced away.

The tall boy loped after them. ‘Wait for me!’

Moving fast, Bianca took out her diary and peeled off her coat. As she hurriedly swapped it for the yellow dressing gown, she knocked the two branches that were the snowman’s arms onto the ground. They gave her an idea. She put on the yellow dressing gown, slipped her diary into a pocket and, flipping up the collar, she crossed the gown over her front and tied the belt, hiding her purple jumper. She kicked snow over the two branches on the ground, covering them up.

When the others came back with arms full of fabric, she grabbed a sparkling sheet, threaded with silver, and a fluffy white blanket. She pretended to dress her snowman, but when the others were busy she grabbed the branches, turned and ran.

On reaching the igloo, Bianca called for Pordis to come out.

‘We’re going to pretend,’ Bianca said, throwing the fluffy blanket over Pordis’s back so that it hung down on either side and hid her legs, ‘that you are a snow pony who desperately wants to be a reindeer.’

‘But I am a reindeer!’

‘I know, but they’re not looking for a girl in a yellow dressing gown with a silly snow pony.’ Bianca grabbed an ice skate and slashed at the sparkling sheet, ripping it into ribbons. ‘I’ll make fake antlers with the branches and a tail like a pony’s out of these ribbons.’ She knotted the ribbons, tying them together. ‘I’m going to make a hat from the branches and strap it to your real antlers. Hopefully it will make them look fake.’

‘And this is a good disguise?’ Pordis asked, looking perplexed.

‘No.’ Bianca laughed. ‘It’s terrible, but you’re a difficult creature to conceal, unless we saw off your antlers.’

‘Don’t you dare!’

‘Silly snow pony it is, then!’

It was a very strange reindeer that shuffled away from the igloo. Bianca thanked the puffins and led Pordis towards the fairground by her homemade bridle.

‘Sway a little from side to side with each step,’ Bianca whispered. ‘Try not to be so graceful. Snow ponies lumber a bit more on account of their stubby legs, or at least Shetland ponies do, and I think they’re nearly the same.’

A grinning boy with a white hawk on his arm pointed at Pordis. ‘What kind of creature is that?’

‘This is a reindeer,’ Bianca answered, then behind her hand whispered loudly. ‘She’s a snow pony, but she wants to be a reindeer, so I made her antlers.’

‘Hello, Mrs Reindeer,’ the boy greeted Pordis with a laugh. ‘Nice antlers you’ve got there.’

To Bianca’s surprise, Pordis snorted air through her nose and made a whinnying sound just like a horse.

The boy winked at Bianca as she carried on, and after a minute she heard him telling another child about the snow pony that thought it was a reindeer.

‘Pordis, that was brilliant,’ Bianca muttered.

‘Oh yes, I am very adaptable. I can be a goat, a pony, even a reindeer!’

Bianca chuckled, turning as she heard the sort of twinkling music that might accompany a troupe of dancing imps. It was coming from the Flurry Flake Ferris wheel. As they drew nearer, it occurred to her that from up there she’d be able to see the whole of Winterton.

‘Pordis, we’re going to take a ride on the big wheel.’

‘Must we?’ Pordis sounded less than enthusiastic. ‘I’m not a bird.’

‘I want to see Winterton from up there,’ Bianca replied. ‘Once we’re in the carriage and the wheel is turning, we’ll be safe from discovery for a bit.’

‘All right,’ Pordis grumbled. ‘Perhaps I’ll be able to take this blanket off for a little while. You’ve no idea how hot it is under here.’

When the Flurry Flake came to a stop, Bianca steered Pordis to join the queue.

The carriage Bianca and Pordis stepped into was a giant glass bauble etched with stars. Inside, the floor and seat were covered in plush white velvet.

As the car rose, Bianca felt the weight of fear lifting from her shoulders. They were safe in here while the wheel turned. She stared out across Winterton, and when they reached the top she moved in her seat to gaze at the ice fortress. She couldn’t see any windows. It looked like a cluster of giant stalagmites. She wondered what kind of queen lived in a place like that.

What had Pitter and Patter said? ‘She mustn’t find the boy . . . He’s the queen’s favourite toy.’ She felt certain they’d been talking about Finn. But who was this Queen of Winterton?

She imagined how cold and severe the dungeons would be in a fortress like that, deep within the glacier. She desperately hoped Finn wasn’t in there, and wished she could recall how he’d been taken. Her mind was full of blanks, snowdrifts covering up memories.

Pulling her diary from the dressing-gown pocket, she flicked through it, page by page, realizing she wasn’t even certain what day it was today.

An entry on the page for the first of December caught her eye: FINN FROZEN. What did that mean? She read some notes about a silver book. They made no sense to her, although she remembered that the grey twins had accused Quilo of leaving a book behind. Had she taken it? She couldn’t remember.

On the second of December, she had written SOPHIE & CASPER FROZEN. But she had seen both Sophie and Casper today and they were fine.

‘It’s a puzzle,’ Bianca muttered to herself, looking out at the children playing in Winterton as the carriage descended. More and more of them seemed to be arriving all the time. Did they all have splinters in their hearts? She now saw the town for what it was: a dazzling distraction, a magician’s trick. The rides and games were designed to keep children playing while their hearts slowly froze.

For the first time since she’d woken up here, Bianca truly felt the peril of this strange, snowy land. As the wheel turned, she looked down at the laughing girls and boys, eating ice cream and frozen yogurt below her. A train of sledges pulled by teams of huskies was setting off. The sledges were full of grinning passengers. None of them knew the danger they were in.

‘I don’t like it here,’ she said eventually.

‘Yes,’ Pordis agreed. ‘If reindeers were meant to go up into the sky, we’d have wings.’

‘Not on the wheel! I mean Winterton.’ Bianca smiled at Pordis. ‘But I think the ride is coming to an end now.’

‘Finally!’ Pordis exclaimed, getting to her feet.

When the Flurry Flake halted, they climbed from the carriage and Bianca heard a jaunty tune being played on a flute, accompanied by delicate chimes. In her diary, it said that she was having flute lessons. ‘Where’s that music coming from?’ she wondered, looking around.

‘Over there.’ Pordis pointed with her antlers.

The Winterton children were crowding towards a large white marquee. Boys and girls, and their companion creatures, flooded through the open side of the tent.

‘Let’s join the crowd,’ Bianca said to Pordis. ‘There’s safety in numbers. When we get inside, we’ll find a spot in the middle of the audience.’

The floor of the tent was covered in sheepskin rugs and the walls were decorated with floaty drapes. At the far end, on a raised platform, was a band of musicians.

At the back of the stage a walrus was using his blubbery body as a percussive instrument, slapping and beating time with his flippers. Beside him, a dopey-looking musk ox was emitting a hypnotic bass hum, which rose and fell to a melody an Arctic fox played on a silver flute. The fox was flanked by a pair of biscuit-white seals blowing into pan pipes using their nostrils. At the front, an Arctic ermine ran backwards and forwards, plucking on the strings of a harp. A string of icicles hung along the top of the stage and, perched above them, was a snowy owl, which bobbed her head, hooted and then pecked a couple of icicles, making them chime delicately. The star turn of the band was a giant polar bear sitting on his haunches in the middle of the stage, rubbing the wet pads of his paws round the rims of ice bowls containing different amounts of water. The music was strange and hypnotic.

‘It’s a show!’ Bianca whispered to Pordis as they sat down in the middle of a group of children. ‘Do you think Finn is here?’ She scanned the faces of the children pouring into the tent. There were so many of them, hundreds it seemed.

As the mesmerizing music built to a climax, a troupe of six penguins slid onto the stage on their bellies. They leaped to their webbed feet, with their flippers held up high. The audience of children applauded.

A hush fell as the penguins danced, dipping their heads to the music, weaving between one another in a reel, lifting their feet one way then the other. One of the penguins, the third in line, got distracted and waved a flipper at them, falling out of time. The children beside Bianca giggled and waved back.

The musk ox bellowed out a low trumpeting sound and the walrus beat his flippers against his chest in a drumroll. A seventh penguin was lowered from above the stage on strings, swinging above the heads of the six dancers, looking self-important as he pretended to fly.

Bianca smiled, despite herself. Lots of children were laughing.

The out-of-time penguin was distracted by the laughter and trod on the foot of the bird next to him, who fell over.

Bianca chuckled, glancing across the clapping, cheering audience, hoping she might spy her brother’s toothless grin, and suddenly her heart clenched.

The grey twins were walking through the audience, checking the children and their creatures. They were looking for her. She knew it. But if she and Pordis got up and moved they’d be seen.

She was trapped.