After driving for several minutes through the labyrinth of the Royal South London Hospital grounds, Lynn halted the Peugeot in frustration in the driveway outside the Emergency entrance, as the way ahead was barred by a metal barrier. It was just after half past nine in the evening.

‘Jesus!’ she said, exasperated. ‘How the hell is anyone supposed to find their way around here?’

It was the same every time; they always got lost here. Construction work was going on constantly and the liver unit was never in the same building twice – at least, that was how it seemed to her. And since the last time, a good two years ago, the whole traffic layout appeared to have changed.

She stared around in frustration at the institutional-looking buildings surrounding them. Tall monoliths, a mish-mash of architectural styles. Close to the car was a barrage of red, yellow and pale green signs and she had to strain to read them in the glow from the street lighting. None contained the name of the wing she was looking for, the Rosslyn Wing, which she had been told to access via the Bannerman Wing.

‘Must be in the wrong place,’ Caitlin said, without looking up from her texting.

‘Is that what you think?’ Lynn asked, more good-humouredly than she felt.

‘Uh huh. Like, if we were in the right place, we’d be there, wouldn’t we?’ She tapped her keys in furious concentration.

Despite her tiredness and her fear and her frustration, Lynn found herself grinning at her daughter’s curious logic. ‘Yes,’ she said. ‘Quite right.’

‘I’m always right. Just have to ask me. I’m like the Oracle.’

‘Perhaps the Oracle could tell me which way to go now.’

‘I think you’ll have to start by reversing.’

Lynn backed a short distance, then stopped alongside more signs. Hopgood Wing, she read. Golden Jubilee Wing. Main Hospital Entrance. Variety Club Children’s Outpatients. ‘Where the hell is Bannerman?’

Caitlin looked up from her texting. ‘Chill, woman. It’s like a television game, you know?’

‘I hate it when you say that!’

‘What, television game?’ Caitlin teased.

‘Chill, woman! OK? I don’t like it when you say that.’

‘Yep, well, you are so stressed. You’re stressing me.’

Lynn looked behind her and began reversing again.

‘Life’s a game,’ Caitlin said.

‘A game? What do you mean?’

‘It’s a game. You win – you live, you lose – you die.’

Lynn brought the car to a sudden halt and turned to face Caitlin. ‘Is that what you really think, darling?’

‘Yep! They’ve hidden my new liver somewhere in this complex. We have to find it! If I find it in time, I live. If I don’t, tough shit!’

Lynn giggled. She put an arm around Caitlin’s shoulders and pulled her close, kissing her head, breathing in the scents of her hair shampoo and gel. ‘God, I love you so much, darling.’

Caitlin shrugged, then in a deadpan voice said, ‘Yep, well, I’m quite worth loving really.’

‘Sometimes!’ Lynn retorted. ‘Only sometimes!’

Caitlin nodded, a resigned look on her face, and resumed her texting.

Lynn reversed out on to Crystal Hill, drove a short distance forwards and finally found the main entrance for vehicles. She turned left into it, passed a cluster of yellow ambulances parked outside the curved glass façade of an almost incongruously modern block, then finally saw the Bannerman Wing sign and turned right into the car park opposite a Victorian building that looked as if it might recently have had a facelift.

A couple of minutes later, carrying Caitlin’s overnight holdall, she walked past a man wearing a coat over his hospital pyjamas who was sitting on a bench beside a floodlit statue, smoking a cigarette, and entered the columned entrance porch of Bannerman Wing. Caitlin, dressed in a lime-green hoodie, ripped jeans with frayed bottoms and untied trainers, trailed behind her.

There were twin vertical perspex signs in front of them, printed with the words ROYAL SOUTH LONDON, and a row of white columns stretching ahead down the hallway. To the right was a visitors’ information desk, where a large black woman was on the phone. Lynn waited for her to finish the call, glancing around.

A bewildered-looking grey-haired man with a red holdall in one arm and a black handbag in the other was shuffling forwards in slippers. To her left, a cluster of people sat around in a waiting area. One, an old man, was in a motorized wheelchair. Another old man, in a beanie and tracksuit, sat slumped on a green stool, with a wooden walking stick out in front of him. A youth in a grey hoodie and jeans was plugged into an iPod. A young man, with despair on his face, wearing a blue T-shirt, jeans and trainers, was seated, bent forward, his hands clasped between his thighs, as if waiting for someone or something.

The whole place seemed filled with a late-night air of tired, silent desperation. Further along she saw a shop, like a small supermarket, selling sweets and flowers. A shell-suited elderly woman with blue-rinsed hair emerged, opening a chocolate bar.

The woman behind the desk ended her call and looked up pleasantly. ‘Can I help you?’

‘Yes, thank you. Shirley Linsell in the Rosslyn Wing is expecting us.’

‘Can you give me your names?’

‘Caitlin Beckett,’ Lynn said. ‘And her mother.’

‘I’ll tell her. Take the lift to the third floor and she’ll meet you there.’ She pointed down the corridor.

They walked along, past the shop, past signs reading, BUTT OUT, SMOKING BAN IN ALL NHS HOSPITALS AND DON’T INFECT. PROTECT and past weary-looking, disoriented people coming in the opposite direction. Lynn had always been spooked by hospitals, remembering the countless visits to Southlands Hospital in Shoreham when her father had had a stroke. Other than maternity wards, hospitals were not happy places. Hospitals were where you went when bad things happened to you or to people you loved.

At the end of the corridor they reached an area, in front of the steel doors of the lift, that was bathed in an iridescent purple light. It was more like the light she would expect to find in a disco, or on the set of a science fiction film, Lynn thought.

Caitlin paused from her texting to look up. ‘Cool,’ she said with an approving nod. Then, in a breathless rush of excitement, ‘Hey! You know what, Mum? This is a clue!’

‘A clue?’ Lynn questioned.

Caitlin nodded. ‘Like beam me up from Star Trek, right?’ Then she grinned mysteriously. ‘They put this on for us.’

Lynn gave her daughter a quizzical look. ‘OK. So why did they do that?’

‘We find out on the third floor. That’s our next clue!’

As they rode the slow lift, Lynn was pleased that Caitlin seemed to have perked up. All her life she had had strong mood swings and recently the disease had made them worse. But at least she was coming in here with a positive attitude, for the moment.

They stepped out on the third floor, to be greeted by a smiling woman in her mid-thirties. She was pleasant-looking, a classic English rose face framed with long, brown hair, and she was dressed in a white blouse, with a knitted pink top and black trousers. She gave Caitlin a warm smile first, then Lynn, then turned back to Caitlin. Lynn noticed she had a tiny burst blood vessel in her left eye.

‘Caitlin? Hi, I’m Shirley, your transplant coordinator. I’m going to be looking after you while you are here.’

Caitlin eyeballed her levelly for some moments and said nothing. Then she looked down at her phone and resumed her endless texting.

‘Shirley Linsell?’ Lynn asked.

‘Yes. And you must be Caitlin’s mum, Lynn.’

Lynn smiled. ‘Nice to meet you.’

‘I’ll take you along to your room. We’ve got a nice single room for you, Caitlin, for the next few days. And we’ve arranged an overnight room nearby for you, Mrs Beckett.’ Addressing them both, she added, ‘I’m here to answer any questions that you have, so please ask anything you like, anything at all that you want to know.’