Alastair watched his retreating back, but Susannah couldn't read his face.

On the way, they talked about Christmas his in Cambridgeshire, hers at the house. His mother-in-law was a handful, and he made her laugh with a Christmas morning story about bread sauce and a Kathryn so incandescent with rage that she'd had to go to the spare room and bite a pillow so hard she'd torn the embroidery and had then sat up Christmas evening repairing it with one of those hotel kits. She told him about Daisy and Seth, and the row, and he shook his head, and said he was in no hurry for the girls to grow up. They both marvelled at the news that their baby brother was to have a baby of his own. Al chatted easily about work, and his hopes for the meetings he had coming up. She offered a few details of work.

In the restaurant, they sat in the foyer and drank a beer while they waited for the food.

'How's Amelia?' Alastair's face was grave, and the sparkle had gone completely from his eye.

'Mum told you?'

'You should have told me.'

'Amelia doesn't want any fuss.'

'And would I have made any?'

'I don't know. I never quite know, when it comes to you and Amelia.'

He shook his head ruefully. 'You've never really believed I'm not still carrying a torch for her, have you?'

'Well, are you?'

'I'm married. To the most fantastic, gorgeous, sexy-as-hell woman who knows me inside out and loves me anyway. We have three kids together.'

'And ...'

He laughed out loud, throwing his head back. 'You don't give up.' Then, 'And I'll always, always, always have a soft spot for Miss Amelia Lloyd.'

'I know.'

He nudged her. 'One that I'd never in a million years do anything about.'

'I know that, too.'

'Anyone ever tell you you're a know-it-all?'

'You.'

Alastair shrugged. 'She was the first girl I loved, I think. You don't ever really forget that, do you, Sis? You know that more than most, I think.'

'Now who's a know-it-all?' She wasn't ready to talk about it, not even to him.

His face was serious again. 'So, how is she?'

'Tough as old boots. Self-possessed and strong. Brave as hell. Scared to death. Nearly as scared as me.'

Alastair laid an arm around her shoulders. 'She'll be okay.'

'Everyone says so.'

'You okay?' He was talking about Amelia, she knew, but he was also asking about Douglas.

She smiled. 'I'm fine.' It was easier, right now.

'Tell her ... tell her I'm on her team, will you?'

'Like she hasn't always known that?!'

It was funny Susannah had lived in London for years, ever since she'd finished law school. And over those years she'd done all the things a visitor would do most of it with Doug's kids. They'd taken them on the London Eye where, on learning that the cabin took a sedate twenty-five minutes to complete a circuit rather than a hair-raising, roller-coaster-style ninety seconds, Fin had lain spreadeagled on the floor of their pod, moaning that this was the most boring ride he'd ever been on in his life, to the bemusement of the coach party of Dutch tourists accompanying them. He'd displayed a similar ennui at London Zoo. He liked HMS Belfast, but that bored the girls to tears. They liked Hamleys, but that gave Douglas and Susannah a simultaneous headache. She'd seen the Crown Jewels, the Tower of London, the Houses of Parliament and the Cabinet War Rooms (twice). She'd been dragged, eyes mostly closed, around the London Dungeon and she'd bruised her coccyx ice skating at Somerset House at Christmas.

She knew the city well. She knew if a minicab driver was taking a longer route on purpose, and she knew the best places to park if you were shopping on Oxford Street. She had favourite restaurants and cinemas and delicatessens.

With Rob, though, she started to see a different London. After that first drink, he'd sent an email to the work address she gave him. He wasn't taking no for an answer, he said. He didn't have many friends in the city she had to see him again. They started to meet for lunch, after work, on Saturday afternoons when Doug was at home with the kids.

She hadn't realized how easily she could extricate herself from her daily life and how little, apparently, she would be missed when she did. It seemed to her that she'd extricated herself emotionally a while back the physical stuff was much easier.

It would only have been lying if she'd had to answer questions about it. And she didn't.

During the week, her day was her own. If Megan noticed anything different about her, she didn't say so to her face, and Susannah would never have been aware of what she might be saying behind her back. She might have stopped eating so many lunches at her desk, but so what?

And in the evenings, during the week, she and Doug were well past the 'when are you coming home, honey, and what would you like for dinner?' stage an extra hour or two never even raised an eyebrow in a house where two lawyers lived.

Weekends were easy, too, when the kids were there. She'd often 'escaped' in the past, sometimes just walking round the corner to sit with a large coffee and the Guardian for a couple of hours, or shopping, or having lunch with Amelia ...

But now, instead, she met Rob. She met him for lunch, after work, and on Saturdays. At first a couple of times a week, then every other day. Sometimes every day. One morning, as she applied make-up in the mirror in the bathroom, Susannah looked at herself and smiled at the recollection that this was exactly how it had felt the first time. She remembered her mum shaking her head, complaining that she was obsessed, that it was unhealthy. She was as sceptical about that diagnosis now as she had been then. This wasn't bad for her, this was good. This was doing her more good than anything had in a long time.

They never went to his house, or to hers. She never suggested he meet Douglas. She never really talked about Douglas much. And Rob didn't ask. She presumed her freedom and her availability were as eloquent a statement about the nature and state of their relationship as any she might have made.

The only days that were sacrosanct were the appointments with Amelia. She never missed one. But she didn't talk to Amelia about Rob. She didn't want to talk to anyone about it. It was her delicious, blissful secret, and she wanted to keep it.

She was having so much fun. Breathless, wide-eyed, sparkling fun. She realized it had been a long time since she had. They talked a lot, and they laughed. She felt young again. It was cold far too cold to spend much time outside. Their London was, now, a London of museums. Warm, cheap and anonymous, they made the perfect place to meet. They tried the London Aquarium one day, but it was full of school trips, barking teachers and squealing children, and, even though it wasn't actually cold, it felt like it was. The museums were a much better bet. The National Portrait Gallery on St Martin's Place, Tate Modern on the river, The Courtauld at Somerset House, the British Museum. Sometimes they wandered, vaguely interested by an exhibit or a painting; sometimes they found a bench facing a beautiful picture or an interesting sculpture and sat there for an hour. Sometimes they just went to the coffee shop and talked over endless cups of tea that sat and grew cold. Sometimes they didn't talk that much. They looked at each other for long, lovely minutes, taking in every detail of each other's faces. Rob paid her compliments. When she dressed in the mornings, now, she looked at herself through his eyes, choosing things she thought he'd like. She caught herself choosing matching sets of underwear, pulling lacy panties and balcony bras from the back of the drawer for the first time in a long while. It made her feel pretty. He made her feel pretty.

They filled in the gaps of their missing years for each other. It had been a long time. He talked to her about all the places where he'd been posted the Falklands, Scotland, Germany, twice to the USA, a spell back at Cranwell where he'd trained twenty years earlier.

He'd become a great skier, an accomplished horse rider, and done skydives, and bungee jumps. He'd been on every continent except Antarctica, but he wasn't ruling that out. He talked enthusiastically about everything he'd seen and done, and Susannah could have listened for hours, except that he reciprocated every question she asked, anxious not to monopolize the conversation. His physicality was exciting to her. He was a much bigger man than Douglas broader, more muscled. She felt slight beside him. She watched his mouth while he talked, the way his full lips moved across his teeth. The smile that had always melted her still did.

One night, over a bottle of wine in a hotel bar just off Bloomsbury Square where they went sometimes after they'd trawled round the British Museum, he told her unprompted some of what he'd seen in the First Gulf War. The memories were extraordinarily vivid and still painful to recount. He spoke slowly, and without really looking at her. The regiment had been first responders to the scene when an American missile had been fired into a crowded shopping area, missing its more legitimate military target. They'd arrived within minutes, while survivors were still staggering out into the streets, bleeding and burning. It was the first time he'd seen dead bodies, and some of those had been women and children maimed so severely they were almost unrecognizable to the family members who scrambled hysterically through the rubble, screaming the names of loved ones and holding their heads in shock and disbelief. He said he truly believed that he and his buddies had gone into the situation boys and come out men, growing up overnight. His eyes welled with tears in the retelling, and she squeezed his hand, knowing instinctively when exactly that had been, remembering Lois's tearful voice on the phone. Hating that he hadn't been able to tell her, to talk to her then, when it had been fresh.

But sometimes, most of the time, things were much lighter and more frivolous between them. One of their quickly established routines was to fire staccato questions at each other. They'd missed so much they both wanted to catch up.

'Favourite film?'

'The English Patient. You?'

'Haven't seen it. Can't stand Ralph Fiennes. Leon.'

'Got a thing for Natalie Portman, have we? You and the rest of the male population ...'

'Not in that! She was just a kid ... Now ... in Star Wars ... you're talking. Mind you, I always had a thing for Princess Leia, too. Me and the rest of the male population.'

She remembered. 'Favourite song?'

'"Stairway To Heaven". Led Zeppelin. Hands down.'

'Saddo. I knew you were going to say that. In fact, there are as yet undiscovered tribes in the heart of the Peruvian Jungle ...' his voice joined hers as she finished the sentence and they spoke in unison, '... who knew that you were going to say that.'

It was a line from The Young Ones. They used to say it all the time.

Susannah clapped her hands delightedly.

'How dare you dis the Zeppelin? What's yours, come on ... ?'

She'd been laughing, unable to think of one.

'I bet it's The Fray or Snow Patrol or Coldplay or Keane, isn't it? Come on, admit it. You're a soft rock girl, aren't you? Probably loved the Corrs, too ...'

'Cheeky sod. U2.'

'Which one?'

'I don't know ... any one ... they're all brilliant. The Joshua Tree best album, hands down ...' She never heard a song from that album without thinking of him. The album had come out in 1987, and had been, pretty much, the soundtrack of their time together. She remembered a night at his house, when they'd been playing it, and Frank and Lois had been out on one of their tactful walks. She'd taken her bra off before she went round, and his face, when his hands had snaked up her sweater, at the back, and realized ... his eyelids drooping heavily with lust, his gratifying groan of desire. She remembered tingling with wanting him. She blushed. She saw on his face that he remembered, too, but he concentrated on the game.

'Half a point.' He paused, and his eyes burnt into hers. 'Bloody hell, Susannah.' Then he shook himself out of it. 'Best song on the album ... ?'

'"One".'

'That's Achtung Baby.'

'Smart-arse. It's still my favourite. Still their best ...'

He held his hand flat and waved it side to side. 'Maybe. "With Or Without You"?'

'Maybe. Favourite composer?'

'May I refer you back to my answer on Led Zeppelin?'

'Come on. I'm talking classical music now. You listen to that?'

'I'm not a total philistine, if that's what you're suggesting. I may have a bit of Mendelssohn knocking about somewhere. You? Still a Rachmaninov girl?'

She was impressed. With the Mendelssohn, and the Rachmaninov reference. Dad's favourite, she'd always loved his music. She still did.

'You're impressed, aren't you? Admit it.'

She held her hands up in surrender. 'I admit it. But then, I always was. Does your dad still play Italian opera too loud?'

Rob smiled. 'Absolutely. Rossini, Verdi and Puccini are still top of the hit parade at Mum and Dad's house.'

'Did he ever get you to like it?'

Rob shook his head vigorously. 'Not a chance. Tolerate it, maybe. Like it never!'

When they were young, Frank would sometimes put on an aria or a chorus and translate for them as it played, standing in the living room, acting out the stories melodramatically, his voice and his face full of emotion. They were a tough crowd, she remembered. But then it had never really seemed as though he was doing it for them he used to get lost in the tale he was retelling, his eyes half closed in pleasure or vicarious sadness.

And now, on one of their outings, wandering through the Poetry and Dream rooms at the Tate Modern, Rob slipped his hand into hers, just as he had done that first night all those years ago. It felt as exciting and as thrilling and as right as it had done then. Not just lust, though there was plenty of that still left behind. She was feeling things again that she had thought were part of her past, not her present or her future. There was affection. And memory. And trust. And there was magic. That was the only word for it, she realized. It was like a chemical reaction with a celestial effect. Magic. After that, they held hands every time they were together. Susannah told herself that's all it was, all it would be, as though telling herself would make it so.

One evening, a few weeks after Rob had come back into her life, Douglas came up behind her while she was washing an omelette pan. He snaked his arms around her waist and rested his chin on her shoulder. 'You seem happy lately.'

She closed her eyes and bit her lip, waiting for guilt to wash over her. But it didn't. There was no room in her, she realized. 'I am.'

'I'm glad.' He held her for a moment, then kissed the side of her neck and went back to the television, leaving her bracing her hands against the sink.

She realized she felt nothing physical from his touch. Rob just had to touch her fleetingly, accidentally even, and it was like his skin burnt into hers, and a sensation dropped through her thighs and into her knees, making her feel trembly. Douglas had held her and kissed her, and she'd felt nothing.

No magic.

She'd never thought before, about whether she was a good person or not. These days it was a question she asked herself quite often, and one she couldn't quite answer.

February Susannah woke up with a start at four thirty on the morning of her fortieth birthday. For nearly an hour she lay in bed, listening to Douglas breathing in and out, and hearing the central heating crank into action, willing herself back to sleep. But her brain was too busy, and eventually she gave up, slipping her feet into her slippers and sloping down to the kitchen to make a cup of tea. She put on Radio 4 and listened to the shipping forecast while the kettle boiled.

She sat at the kitchen table and pulled her BlackBerry out of her handbag. The red light flashed. A text. It was Rob. He'd texted ten minutes earlier.

Happy Birthday. Are you celebrating?

He just remembered. She hadn't said a word.

She pushed the reply button and texted back.

Can you meet today? Call me if you're awake.

Within a minute the phone vibrated in her hand, and she answered it before it rang.

'You're up early.'

'Can't sleep. What's your excuse?'

'Twenty years of military life. Happy birthday, Susie.'

'Thank you.'

'So, how do you feel?'

How did she feel? No one else had asked her. There was all the usual fortieth birthday nonsense. Life begins. And in a way, it had.

A couple of months ago, she'd have had a different answer. A couple of months ago, she was acutely aware that the threescore years and ten were more than halfway through, and that she wasn't where she had expected to be. Where she wanted to be.

That feeling had gone, though. And he was the reason.

She had nothing to show for the feeling. She knew that. He was married to Helena. She was living with Douglas. No one knew. There was nothing to know, for God's sake. They hadn't so much as kissed. A bit of teenage hand holding, that was all. Talking. But she knew. She knew.