She had to be brave.

Emma Devern had said this to herself countless times since they'd brought her here. But as the hours dragged into days and still there remained no prospect of her being released back to her mum, it became harder and harder for her to manage it.

They were keeping her in a dank, carpetless cellar with one narrow window coated in grime, high up on one wall and well out of reach, which let in thin shafts of daylight. She had to wear a pair of handcuffs, and was chained to the wall by one ankle. The chain was long enough so she could move around, but she couldn't reach the steps at the end of the room or the far wall, and she knew in her heart that there was no way she was going to be able to escape.

She thought this was the third day she'd been here, which meant it was Friday. It was difficult to know for sure because the days simply flowed into one another, but she was trying hard to keep track. At nights it was cold. She slept on a horrible little bed with filthy sheets and she was forced to wrap herself up in them to keep warm, even though they smelled awful.

On the first night she'd been too shocked about what had happened even to cry. She remembered very little about how it had all started. She was going back to the car after the dentist appointment. Her dentist was called Mr Vermont, after the American state. He always said what good teeth she had, and she did too, because she looked after them well and didn't stuff her face with sweets like a lot of her friends. It had just been a standard check-up. She liked Mr Vermont. He was good-looking with a nice tan, even though he was a bit old and his hair was beginning to go a bit thin on top. The check-up had gone well. For the third visit running nothing needed doing – which was just as well because she hated having her teeth messed about with – and she'd been in a good mood as she crossed the car park at the front of the building.

Pat had been in the driver's seat with the paper in front of him, checking the sports pages, like he always did, but as she opened the door and got inside, something immediately felt wrong. He didn't greet her like he usually did, with a big grin and an 'All right, baby, how'd everything go?' in his rough London accent. Instead, he turned and stared at her, and she saw that he looked really frightened. His eyes were wide and there was sweat running down his forehead.

Then she heard a noise behind her, a kind of shuffling, and before she could even take in what was happening she was grabbed round the neck and pulled back into the seat. The next second, a wet cloth that smelled of chemicals was pushed against her face, and suddenly she couldn't breathe any more and she was struggling and kicking, trying to attract attention, help, anything…

It was all over so quickly, even now it didn't feel quite real. Her last image was Pat turning away from her and starting the car's engine with a low rumble. Then everything went black, and she couldn't remember another thing until she'd woken up in this cold, featureless room with a terrible headache and feeling really sick.

She wondered what had happened to Pat. She'd always liked him. He was good fun. They liked to joke together, and he seemed to make her mum happy. At first she hadn't been sure about him. She was used to it being just her and her mum. That was the way it had always been, the way she'd always preferred it. She didn't know her real dad. She'd never met him and she didn't even know who he was. Whenever she asked her mum about him, she'd always said that it was just a man from a long time ago, that he'd gone away, and that it would be best just to forget about him. She wanted to find her dad, but she didn't push it with her mum, and anyway, Pat made quite a good dad. And her friends were jealous because he was nice-looking, and not too old either.

She hoped they hadn't done anything bad to him.

'They' were the two men who were keeping her prisoner. She was not allowed to see them, and had to put on a black hood like something an executioner in a medieval history book might wear whenever the cellar door opened. One of them wheezed when he walked, making a horrible sound like something out of a horror film. She might not have been able to see him, but she could always hear his approach. And she could smell him too. He absolutely stank, a really horrible combination of BO, old socks and toilets that was so bad she thought she might gag whenever he got too close to her. He was the one who usually came down twice a day to check up on her. He'd bring food – Marmite or jam sandwiches, and fruit – and change the bucket they made her use as a toilet.

When he'd come down on that first night, telling her to put on the hood, she'd been absolutely terrified. But he'd told her not to worry, that no one would hurt her, and that she'd be going home soon, and even though he'd talked in a strange rasping voice as if he was trying to disguise it, and had stroked her arm with cold, gloved hands, his touch lingering that little bit too long, something told her that he meant what he said.

As time wore on she'd begun to lose hope of going home and being reunited with her mum and her friends, and everyone she cared about. But she had to be brave. She just had to be. It was just that she really didn't want to die. She was happy. She'd never done anything wrong, and she couldn't see why anyone would do this to her. It wasn't fair. And when she thought about what might happen to her, she got really scared. Although she trusted the smelly one, she definitely didn't trust the one he was working with.

He'd only been down once, on the second night. When he'd called out to her from the top of the stairs, telling her to put on the hood, his voice was harsh and cruel, with no kindness in it at all. She'd done what she was told to do and had then sat there waiting, but she hadn't heard his approach. He was that silent on his feet it was like he was a phantom. All that told her he was in the room was the faint smell of cigarettes, and a feeling that someone was watching her.

After a while she'd asked uncertainly whether there was anyone there.

'Yeah,' came the reply, like he was mocking her. 'I'm here.'

'What do you want?'

'You're going to talk to your mum. You're going to tell her that if she pays the money, then you'll be going home tomorrow.'

She felt a rush of excitement. 'And will I?'

'If she does what she's told, yeah,' he answered, but it didn't sound like he meant it. 'Now turn round on the bed so you're facing the wall.'

She did what she was told.

'Bet you're not used to being told what to do, are you? Little rich girl like you. Bet you usually tell the servants what to do, don't you?'

'I don't have servants,' she said quietly. 'I'm just normal.'

'You don't know what normal is, you little bitch.'

'Why are you doing this to me?' she asked, because she really didn't understand why he was being so cruel to her.

'You don't ask the questions,' he said, ripping the hood from her head in one movement. 'You obey orders. Keep staring at the wall, and remember what you've got to tell your mum. If she does what we say, you go home tomorrow.'

He'd pushed a phone roughly against her ear and a couple of seconds later her mum had come on the line. Emma felt a huge burst of emotion. She wanted to cry so much but she knew she had to hold it together for her mum's sake, so she'd said she was fine and that if the money was paid she'd be back tomorrow. She'd wanted to say more but the phone had been snatched away with a hissed 'Don't turn round', and then a few seconds later she'd heard the key turn in the lock of the cellar door.

After he'd gone, she'd sat there shaking for several minutes, part of her feeling hope now that she'd heard her mum's voice, but a much bigger part feeling fear. She'd never come across anyone truly evil before, and now that she had, it made her wonder whether she was ever going to get out of here alive. Because they hadn't let her go, like he'd said they would. She was still here, hoping that the smelly one would keep the cruel one from doing anything to her, which was why she'd been as nice as possible to him whenever he came down.