The corridor of the train was even colder than the carriage. Lydia looked in both directions and was relieved to see no one else plagued by insomnia or feeling the urge to stretch their legs, though it stank of pipe tobacco, as if someone had been out here recently. The corridor was brown. Like climbing inside a long brown tube with only one dim light set high up on the wall. Lydia liked the gloom. It soothed her. Helped her think more clearly.

The train shuddered to the monotonous rhythm of its wheels and Lydia pressed her face to the cold glass, but she could see nothing outside except the night itself under its thick black blanket. No lights out there, no towns, no villages. Just a frozen, never-ending wilderness of trees and snow.

How on earth did they build the railway out here? The scale of Russia, like the scale of China, took her breath away and she struggled to cram the size of them into her head. Instead she’d learned to focus on the small things. She was good at that, seeing the things others missed. Like the sun flaring on a man’s pocket watch or the corner of a wallet jutting out of a jacket, or a lady’s gold lipstick case left for no more than a second on a shop counter. Lydia couldn’t help a faint smile. Yes, she’d been good at that.

Abruptly she shifted her gaze from the blackness outside to her own reflection in the glass. She grimaced. The hat was truly hideous, a brown wool thing with a wide peak that made her look like a baboon. She was glad Chang An Lo wasn’t here to see her in it. She sighed and could hear her fears crackle like biscuit crumbs in her breath. She was seventeen; he was nineteen, nearly twenty. Would a man wait indefinitely? She didn’t know. He loved her passionately, she was certain of that but… A dull flush of colour rose to her cheeks at her own naivety. How long could a man be without a woman? A month? A year? Ten years?

She knew she’d wait a lifetime for him if she had to. Is that what her father had done? Waited year after year in a labour camp for her mother to come?

Suddenly Lydia yanked off the hat and tossed her head so that the tumble of copper waves leapt into life and framed her face, rippling over her shoulders. It gave her a look of wildness that satisfied something in her. A lioness, someone had once called her. She dragged her fingernails down the glass, ripping tracks through the film of mist that her breath had painted on it, sharpening her claws.

It was just before dawn. Lydia was watching the light shift from the intense darkness that cloaked northern Russia, black as the coal that was hauled up from its depths, to a pale translucent grey. Trees began to emerge like icy skeletons. The world was becoming real again.

She headed up the gloomy corridor towards the tiny washroom at the end. A queue of three passengers had already formed outside it. Russians, she’d noticed, were good at queuing, unlike the Chinese. As she leaned against the wooden panelling and felt the constant turn of the wheels echo through her bones, her thoughts centred on the woman back there in the carriage, the one who’d asked where she came from. She made Lydia nervous.

Suddenly there came the sound of quick light footsteps hurrying towards the washroom. Lydia had shuffled her way up to second place in the line. Not that she was in a rush to use the squashed little facility, but she wanted to delay her return to the carriage. The footsteps stopped. Lydia looked behind her and was astonished to see a queue of four women and a child – when had they arrived? – all waiting patiently, clearly rural workers with headscarves and shawls and big-knuckled hands that laboured hard in the potato fields. Their faces were uncommunicative, their thoughts private. The child, a small boy in a cap, was nibbling at his thumb and making little mouse noises to himself. Behind him stood the new arrival. Lydia felt a jolt of surprise, though she shouldn’t have. It was Antonina, the wife of the camp Commandant, and she was wrapped up warm in the silver fur coat.

‘Dobroye utro, comrades,’ the newcomer said brightly. ‘Good morning to you.’ She nodded at Lydia.

The women stared at her the way they would at a gaudy magpie. One muttered, ‘Dobroye utro,’ then looked at the floor. The others remained silent. The child touched a grubby hand to her coat and she stepped away from it. She was wearing the white cotton gloves and started to rub them together awkwardly, fingers curling round each other.

‘Comrades,’ she said, but her brightness was cracking at the edges, ‘I’m desperate.’ She gave them a smile that reached nowhere near her eyes. ‘Do you think I could-?’

The line turned on her.

‘Nyet.’

‘Wait your turn.’

‘My boy needs to go but he doesn’t complain. You should know better.’

Antonina’s deep-set eyes blinked. Her mouth looked fragile. She shook her head and as one hand started to scratch the back of the other, a tiny thread of crimson appeared on the white cotton.

‘Comrade Antonina,’ Lydia said pleasantly, as she stepped out of the queue, ‘you can take my place.’

The child’s mother gave her a quick look of disapproval.

‘Comrade,’ she said, her tone quiet and reasonable, ‘we no longer have to let worthless parasites, like this woman in her bourgeois finery, steal our rights from us. She is clearly not a worker. Just look at her.’

Everyone stared at the pale pampered face, at the ruby earrings nestling in the dark hair and at the luxurious fur coat.

‘It’s obvious she is-’

Lydia interrupted. ‘Please, comrade. Pozhalusta. This is not harming you. I’m giving her my place in the queue, so-’

‘Young girl,’ the child’s mother said with interest, ‘what is your name?’

Lydia’s mouth went dry. ‘My name doesn’t matter. It is no concern of-’

The woman pulled a small blue notepad from her pocket. Attached to it by a rubber band was a pencil.

‘Your name?’ she repeated.

The Commandant’s wife said abruptly, ‘Enough of that, comrades. ’ She half turned her head, raising a gloved hand, and immediately one of her uniformed travelling companions appeared like a shadow at her side. He said nothing. He didn’t need to. The women stared at the floor. Lydia didn’t wait for more. She squeezed past his bulk and headed back towards her compartment, but as she approached it she saw the second of the woman’s uniformed guardians blocking her path.

‘Excuse me,’ she said politely.

He didn’t move. Just rested his hand on the gun holster at his hip. He was tall with fine Slavic features and a high colour to his cheeks. His dark eyes were amused.

‘Tell me, girl,’ he asked, standing too close and scanning her coat, her shoes, her ugly hat, ‘what is your interest in our Comrade Commandant’s wife?’

Lydia shrugged. ‘She’s nothing to me.’

‘I’m here to make sure it stays that way.’

‘That’s your business, comrade. Not mine.’

His eyes were no longer amused, but after a long stare he stood aside to let her pass. His uniform smelled stale, as though it had been slept in too many times. She felt his eyes bore into the back of her head as she scurried on down the corridor.

By mid-morning it was raining hard, a grey sleeting downpour that rattled like buckshot against the windows. Without warning as they were crossing a wide flat plain, the train started to slow with disconcerting jerks, the brakes shrieking and clouds of steam swirling alongside. Outside, the world blurred.

A small station with wooden roof-boards and rusting iron railings slowly slid into view, and Lydia felt her pulse quicken the moment she caught sight of the sign. Trovitsk. This was the station for Trovitsk labour camp. No one was allowed off the train here under the eagle eyes of the armed soldiers, unless in possession of an official pass. Nevertheless Lydia rose from her seat.