I wake with a start from a bad dream. Anxiety clutches at my chest. Something's gone . . . something's missing . . . Beth . . . always Beth . . .

As the sensation fades, I grope for the clock beside my bed: 4.15 a.m. Crap. Art is snoring gently beside me. He never wakes early. He never has trouble sleeping. Most annoyingly, he never takes longer than a few minutes to fall asleep.

I get out of bed and pad downstairs to the kitchen. I know from experience that once I'm awake at this time, I might as well get up. I switch on the kettle and fetch a mug, a tea bag and some milk.

I've dreamed about Beth many times in the past few years and though I can never remember the details, I know that she grows older each time, so that she's always the age she would have been if she'd lived.

Maybe the age she is . . . The thought strikes me so hard I actually drop the mug I'm holding. It bounces onto the countertop with a thud that echoes loudly in the early morning air. Could I be dreaming of a real person?

Is such a thing even possible?

I sit down at the table, listening as the rush and hiss of the kettle coming to the boil fills the room. I rarely remember anything specific from the dreams, just a vague and fading sense of her face: once a rosy-cheeked baby, then a chubby, smiling toddler and now, almost eight years old, an olive-skinned little girl with soft brown curls, like I had when I was younger, with Art's huge brown eyes.

In my dreams she's alive and she's perfect.

I drink my tea, go back to bed and refuse to let myself think about either Beth or Lucy O'Donnell. After a while I fall asleep again. When I wake up it's almost nine-thirty. I can hear Lilia singing along to her iPod as she vacuums downstairs. I turn over. There's no sign of Art. Which isn't surprising. He's always out the door by seven. There is a note on his pillow, however. I reach over, groggily, and pull it closer.

Wish this was flowers. Love you, Ax I teach today's class in a bit of a daze. I take four two-hour adult-education classes here at the Art & Media Institute each week all on aspects of creative writing. It's not well paid and, as Art pointed out the other day, it's so part-time it's not even really 'a proper job.' I'm waiting for a lift when one of the women from the class corners me. It's Charlotte West, all designer jeans, sleek blonde ponytail and pushy sense of entitlement.

'Geniver?' Charlotte's voice is wheedling, her accent pure Home Counties. 'I wonder if I might have a word?'

I scan the lifts. All three of them seem to be stuck on the first floor so I force my mouth into a welcoming smile. 'Sure,' I say.

Charlotte moves closer and I have to stop myself taking a step away from her. She's in her early forties, I'd guess a little older than me, though roughly the same age as most of my writing classes. She looks good for her age slim and groomed. Today she's teamed her trademark Calvin Klein jeans with an emerald-green boat-neck top that brings out the colour of her eyes.

'How can I help?' I continue.

'I re-read Rain Heart again,' Charlotte says, her eyes shining. 'It's so brilliant. Such an inspiring book.'

'Thank you.' I feel awkward and not just because Charlotte is gushing. Of my three published books, I actually think Rain Heart is the weakest. The plot about a woman whose husband has an affair with the wife of his business partner has more than a couple of holes, and the characters seem wooden and unconvincing to me now. Ironically, it sold better than the others. In fact, it's the only one still in print.

I edge away. Charlotte follows, backing me into the corner between the wall and the first lift. I get a whiff of her perfume one of those dark, sweet, cloying scents meant for velvet dresses and expensive restaurants.

'I was wondering where you got the idea from?' Charlotte goes on.

I sigh inwardly. This is the most common question writers get asked and, to my mind, one of the hardest to answer.

'I thought perhaps the story came from real life?' she adds.

'No.' I hesitate, wondering what to tell her. I could offer up the truth as far as I know it, that Rain Heart came from my imagination: a blend of half-thoughts and ideas filtered through a couple of newspaper articles, five minutes of overheard gossip at a bus stop and the inside track on two friends' heartbreaks.

And yet there's something unsettling about the intensity of her gaze that holds me back from confiding any of this information. 'I'm sorry, Charlotte . . .' I glance pointedly at my watch.

'Oh, right . . .' She sounds a little injured now. 'I'm in a hurry too. If I miss my train from Paddington . . .'

'I know.' I offer her a sympathetic grimace. Charlotte has mentioned her long journey from the West Country to my creative-writing class several times before. She definitely gives off 'the smell of burning martyr', as Hen would say. Other members of the group are now appearing behind her. Out of the corner of my eye I can see the lift furthest away from me has reached the second floor.

'Like I say, I was just curious . . .' Charlotte pauses. She shifts her bag up onto her shoulder and I notice it's an Orla Kiely, identical to the one Hen bought me for my last birthday.

Across the lobby, the furthest lift away from me is opening. Students surge inside. There won't be enough room for all of them, let alone me as well.

'Okay, well, I really have to go.'

Charlotte stares at me intently but says nothing. Her green eyes are impossible to read. For a second she seems almost angry. The lift doors close, leaving several people still outside. I glance at the two remaining lifts. The one nearest me is moving now. Third floor . . . fourth floor . . .

'I'm just so fascinated by your work, Geniver,' Charlotte says. There's a fawning tone to her voice that sets my teeth on edge. I take a step towards the lift as it pings its arrival.

'Bye, then,' I say brightly.

Charlotte's face falls. She tosses her head and her blonde ponytail swishes from side to side. I feel guilty, then irritated. People are crowding around, angling for a spot in the lift as it opens. If I don't move now I'll miss this one too. I step inside.

As people pile in after me, I can hear Charlotte, still outside the lift, sniff loudly.

'Well, good luck with your next book,' she says evenly.

My face burns as two women I don't know stare at me.

I press the button for the ground floor. As the door closes, I wonder if Charlotte knows what she's saying. If she knows I haven't written anything for nearly eight years.

Since Beth.

I try to push this thought away and head off to meet Hen for lunch. As I reach the restaurant I pass a little girl. She's smiling and skipping along beside her mother in a stripy school uniform, with short dark hair in two stiff bunches. I stop and turn, staring after her. A fear rises inside me. In the same way that you notice lovers in the street after you yourself have suffered a break-up, for years I'd see babies in prams and toddlers in buggies and think: 'That's what my Beth would look like now.'

But I never wondered before if any of the children I notice could be my Beth.

The fear increases inside me. I actually take a step after the little girl before trampling on my panicky thoughts. Don't be stupid. Beth is gone. Except . . . my panic rears up again. Maybe she isn't gone. She could be out there somewhere and you would never know, Gen.

Oh God. I force myself to go into the restaurant. I sit down, feeling hot even though it's cool and calm and the room is only a quarter full. I push thoughts of the little girl with her bunches out of my mind and start puzzling over that 50,000 Art paid to 'MDO'. Who or what is MDO?

The restaurant is starting to fill up when Hen arrives, nearly fifteen minutes late. She flies in through the door of the restaurant, her wild hair streaming behind her, her scarf trailing on the floor. She beams at the matre'd, who smiles indulgently at her and escorts her to our table.

That's Hen all over. Pretty and dizzy. On the surface. Underneath, she's as sharp as a pick.

'Sorry, Gen,' Hen gasps. 'I got held up in Cath Kidston.'

I can't help but smile. If there's one sentence that sums Hen up, that's it. Always late, and with a penchant for girly knickknacks. Until she married Rob last year, Hen never had any money yet never seemed to stop spending. I've lost track of the number of times we've been in shops and she's had her cards cut up in front of her. She frittered away most of her twenties in a succession of short-lived jobs which she only managed to hang on to for as long as she did because of her charm and her smarts. Unsuitable boyfriends were also a specialty penniless drifters with endearing smiles and severe commitment issues. No one who knew Hen was surprised when she fell pregnant with Nat or that the father ran away as soon as he found out.

Rob was a surprise. He's ten years older than her, and a banker a breed that the younger Hen would have had put up against a wall and shot. Rob is as grounded as Hen is flighty and, while I believe Hen genuinely loves him, I'm sure she enjoys his money too.

Still, as my mother never tires of reminding me, you can never really understand anyone else's relationship. And the truth is that Hen's been far easier to be around for the past eighteen months, now she's able to indulge her extravagant tastes without worrying about paying her bills.

Hen is on top form. She doesn't mention Lucy O'Donnell's visit for at least half an hour. She's full of the funny shop assistant at Cath Kidston and some quirky expressions Nathan has come up with. I try to put O'Donnell out of my mind too, though her words lurk like a shadow behind everything I think and say.

'Are you okay, Gen?' Hen asks at last, smoothing down her top. It looks expensively cut, with a low neckline and tiny seed-pearl buttons. She casts a glance at my chewed fingernails and the torn, red skin around them and I smile, knowing this is how Hen gauges my well-being.

I tell her how upset Art got last night and then I tell her about the payment to MDO. I feel disloyal bringing it up, but it's on my mind and I can't hide my anxiety from Hen she's too sharp-eyed for that.

'It was fifty thousand pounds, Hen. I mean, that's a huge amount to go out of a personal account.'

Hen shrugs. 'But Art says it wasn't personal,' she insists. 'Fifty grand isn't that much in company terms. Rob's always shifting money around different accounts. And I'm not surprised poor Art was upset after that woman coming round. Bringing all the old stuff up it's going to be stressful for both of you.'

I fall silent. Beth is the one thing I've always found it hard to talk to Hen about. We were pregnant at the same time, though under very different circumstances, and full of plans for how we would be mums together. Nathan was born just a week before Beth. Hen missed the funeral as a result. I know she felt bad about that, but she didn't want to leave her baby and I couldn't cope with seeing a newborn just then. It was hard for both of us to be apart at the very moment we needed each other the most. During the twelve months that followed we spent less time together than we had in years. Hen tried, to be fair. But I couldn't face her and Nathan for a long time. I felt bad about that, but I know Hen understood. She certainly never held it against me.

And yet, though it's never been said, we both know that it's still difficult for me to see her as a mother or be reminded of what my own life as a mother would have been like. At least Hen understood why I needed to call myself a mum after Beth died. Most people seemed to think that made no sense as if I didn't really qualify for motherhood. But, to me, Beth was as real as any other baby and not to be allowed to call myself a mother seemed to deny her very existence. Stillbirth grief is like that full of stupid little heartaches that leave you isolated and floundering. There are no memories to hold on to, no known individual with a distinctive personality to mourn, only a sense of something lost, always out of reach.

Hen puts her hand on my arm. 'I know it's difficult even without some stupid woman making ludicrous claims.' She rests her gaze on me, her normally lively, darting eyes full of sympathy. 'Maybe it would help to look at the certificates and stuff again. Maybe you need to see them all once more to let it go.'

I think about this on the way home. Hen's right, maybe it would help to see all the official documents. The trouble is, I have no idea where Art put everything. Despite my search, I didn't find anything in his office.

It takes me ages to get home. My bus crawls along Seven Sisters Road there has obviously been some kind of accident and all the cars are stopping to have a gawp. Once I'm back, I check out the obvious places the cupboards in the hall and the bedroom and, of course, Art's office, though I already know there's nothing about Beth in there unless it's in that locked cupboard.

I find nothing.

Art walks in at ten that evening. I can hear him on his iPhone as he trudges up the stairs. 'But is that volume or value, Dan? We gotta be clear.'

Art ends his call as he enters our bedroom. There are dark shadows under his eyes and his shirt is creased. He looks exhausted, but happy. I lie back against the pillow and watch him cross the room.

'Hey,' he says, sitting down on the bed beside me.

'Hey.' I ask about his day and Art talks for a while about the meeting at 10 Downing Street.

'. . . and then the PM came in. He's much shorter than he looks on TV and he's definitely had botox or whatever. No lines on his forehead at all. He made a special point of thanking me for being there. Sandrine and I got the policy wonks to talk about their Work Incentives programme, especially the stuff about increasing productivity through demonstrating ethical decision-making. The PM couldn't believe the Loxley Benson figures.' Art grins. 'He listened, Gen, he really did.'

'Sounds brilliant,' I say. I mean it, but at the same time my mind is running obsessively over everything I've been thinking about all day. I wait for him to stop talking, then I take a deep breath. 'Art?'

He looks up. 'What?'

I meet his gaze. 'I'm really honestly not saying I believe anything that mad woman said yesterday, but like I told you, it did bring everything up again. It . . . it made me want to see Beth's death certificate, but I don't know where it, where anything is . . .'

'Gen . . .' Art shakes his head, his body visibly tensing. 'What's the point in going over all this again? You're just torturing yourself.'

I shrug. 'Sometimes I need to go back to go forward.'

Art shoots me a tired smile. 'You're crazy,' he says affectionately.

'Sure, I'm crazy.' I try to smile too. 'So where are all the papers from back then?'

I'm so expecting him to tell me that they've been lost or that he can't remember, that it comes as a complete shock when Art swings his legs off the bed and stands to face me, a look of weary concern on his face.

'They're in the locked cupboard in my office,' he says. 'I put them there because I don't like looking at them. I'll get them now.'

And before I can respond, he's walked out.

I sit on the bed, my stomach in knots. Am I being cruel to Art over this? I think back to that first week after the stillbirth . . . I can't remember much at all. Just a few random snatches of conversation. I do remember Art talking about the funeral he wanted a cremation, but insisted it should be a joint decision. At the time it seemed like the most insignificant detail in the world. But now it means there is no body to dig up. No proof of death.

I shiver. I'm being morbid.

Upstairs the floorboards creak violently as Art walks around his office. I lie back on the pillows.

We scattered Beth's ashes the following April. I'd been seeing a therapist, at Art and Hen's suggestion, for several months and felt like I was starting to emerge from the dark sea of my grief, tipping my face at last to the spring sunshine. Of course what I didn't realize then is that grief, like the seasons, is cyclical. I would just start to feel open to life again, then find myself thrust back under the water, drowning in loss. Perhaps if I had fallen pregnant that year it would have been different, but I didn't. And every attempt at IVF pushed me deeper and deeper back beneath the waves.

There's a final creak from Art's office floorboards, the sound of his footsteps thundering down the stairs, and he's back, a red shoebox under his arm. He sets it down on the bed.

'Everything's in here.' He doesn't meet my gaze. 'I'm going to take a shower.'

He disappears into the bathroom. I know he's hurt, that he doesn't want me upsetting myself by raking it up . . .

But I have to face the truth.

Heart racing, I lift the lid off the red box. The first paper I pick up is the death certificate. I stare at Beth's name chosen in the first flush of our grief because it sounded so delicate and fragile, a soft, simple, sigh of a name. Beth Loxley. It's strange seeing it written down. I trace my finger over the words the name of a person who was never properly a person. There's no word for what Beth is, just as there's no word for the mother of a stillborn baby. I don't mind the lack of a label, but it makes what happened harder to talk about. Of course, talking isn't easy either. When strangers ask if I have children I have to choose whether to explain about Beth, which feels too intimate, or simply say 'no', which feels like I'm denying her again.

I sift through the papers. I'm not any sadder for seeing these, I realize. They're mostly official forms, just facts and figures. Underneath the Registrar's death certificate is the medical certificate of stillbirth, signed by Dr Rodriguez. I remember Art explaining to me that he had to take this to the Registrar to get the death certificate. I examine it closely, then filter through the rest of the papers most of them to do with the funeral arrangements. There's a leaflet subtle and understated for Tapps Funeral Services and a letter from Mr Tapps himself, offering his sympathy for our loss and outlining various practicalities such as the booking of the crematorium and the date of the funeral.

I don't want to think about the funeral right now but, even so, Beth's tiny coffin forces its way into my head . . . The two white lilies Art and I placed on top of it and the numb whisper of my soul as I stared at them.

Inside the bathroom I can hear the shower running.

I close my eyes. What am I doing? Art was stricken at that funeral. He could barely walk. How can I make him go through all this again?

Enough.

I pick up the bundle of papers. As I place everything back in the box, a business card floats out onto the bed. It's Dr Rodriguez's card, with the number and address for the Fair Angel. In the bathroom the water stops running. I hesitate for a second, then for reasons that I refuse to articulate to myself, I slide the Tapps letter and the business card under the mattress beneath me. I put everything else back into the red box, replace the lid and push it away across the bed.

A minute later and Art's out of the shower. He walks towards the bed, a towel wrapped around his waist. He still works out at weekends sometimes, but the muscles in his arms aren't defined like they used to be and there's definitely the beginning of a slight paunch around his middle. We're both getting older. Sometimes I can almost sense time as a force of nature, racing relentlessly into the future, with Art at the heart of the ride and me watching from the sidelines, unable to join in.

'Found what you were looking for?' He still sounds hurt.

'Yes.' I hesitate. 'Did you check out what that MDO payment was for?'

'No,' he groans. 'I forgot, but I know it was some sort of business loan. I just can't remember the details.'

'Right.' I'm wondering if that is really true. Art never forgets anyone he's done business with.

'Right, okay, well when you get a moment . . .' I say, vaguely. 'Thanks for getting everything out for me.'

Art nods, then whisks the box away. He takes it upstairs, back to his office, then comes back and flops into bed.

'I'm knackered.' He sighs, then picks up his phone and starts scrolling through emails. With all the international business Loxley Benson is involved in, there's not an hour of the day when people don't try and contact him.

I get up. The house is cold, the heating has gone off. I pull on a pair of thick socks and pad downstairs. Lucy O'Donnell's phone number is still in my coat pocket. I take it out and creep into the kitchen. I stop at the door and listen. No noises from upstairs. Art must still be busy with his emails.

I unfurl the scrap of paper and stare at Lucy's neat handwriting. The carefully printed numbers look more like the work of a primary school teacher than a con artist. I hesitate. I don't know why I need to speak to her again. I don't even know what I'm going to say. I just know that I can't let it go, like Art wants me to. If I'm going to take things any further then I need as much information as I can get. I mean, suppose just some of Lucy's story is true? Not the part about Art being involved, of course, but babies can be stolen, can't they? And once an idea has been planted in your head, you can't just toss it out again. You have to follow it through to the end.

I move silently through the kitchen without turning on the light and into the utility room. Hands shaking, I take a deep breath and call Lucy O'Donnell's number. It's unobtainable. I don't even get the chance to leave a message. I wait a couple of minutes, then try again, just in case. Still nothing. Maybe it's just as well. Surely this is all the proof I needed that the woman was a flake. Crazy. Deluded.

I save the phone number on my mobile, then throw the scrap of paper in the bin. As I come back out into the hall I hear the creak of the office floorboards on the second floor. I stop, my heart racing. Is Art up there again? Did he somehow hear me down here making a call? Why did that make him go back up to his office?

I wait a few seconds. There are no more floorboard noises. Then I go up the stairs to our bedroom. Art is lying on the bed, just where I left him. He looks over as I walk in. 'What is it?' he asks.