Finn took another swig of rum and then lay beside her. 'I read somewhere that there are more stars in the universe than grains of sand on earth.'

'I never noticed them in London.' They were faded by street lights, car headlamps, over-illuminated office buildings, and the glow of millions of homes. She thought of her sister somewhere in the city. It would be morning and Mia imagined her at her desk, leaning close to a computer screen, her face serious. 'I wish Katie could see this.'

Finn raised himself onto his elbows. 'You miss her?'

'Sometimes,' she said, surprised by the tug to her heart.

'Are you going to talk to her about Harley?'

She shook her head, realizing how dizzy the rum had made her. 'I don't want her to know we're half-sisters.'

'Why?'

'It dilutes us.'

'What do you mean?'

Alcohol had always found a way of working into the closed channel of her emotions, allowing her feelings to flow more easily into words. 'Mum had an affair. Do you think Katie would want to hear that? It means we've got different fathers. It stretches apart what's left of our family.' She sighed. 'And she'd want to know all about Harley.'

'So?'

'So I'd have to tell her everything that he drank and took drugs, that he could be insular sometimes and wildly out of control at others, that his friends and family eventually lost faith in him. And the whole time, she'd be matching parts of him to me.'

'You need to let this go, Mia. You're nothing like Harley.'

'Aren't I?' she said, thinking of the other dark similarity they shared. 'Harley had an affair with his brother's wife.'

'Exactly! You-'

'I had sex with Ed.'

'What?' he said, sitting up. 'When?'

'A month or so before we left.'

'Did you ... do you care about each-'

'No!'

'Does Katie know?'

She shook her head.

'Will you tell her?'

Mia sat up too and her head spun. She pressed a hand to her forehead as if to hold her thoughts still. 'She loves him.'

A pause. 'So why did you do it?'

'I was angry.'

'Angry?'

'At Katie. At you.'

'Mia?'

She could feel the anger simmering inside her, bubbling into her throat. 'Do you know what it is like having Katie as an older sister? It's like you're always standing in the shade. Every guy in school was in love with her. She was the popular one, the smart one, the one who made the right choices.'

'Come on, that's not-'

'Do you remember Mark Hayes from school? He was two years above us and got the sports scholarship to Ranford Manor?'

'Yes.'

'He went out with me for four weeks just so he could come round to our house to gawp at Katie. And I let him.'

Finn said nothing.

'You were the only one who looked at me first when you entered a room.' The wind snaked in from the sea and lifted the ends of her hair. 'And then suddenly you were with Katie.'

He looked down at his hands.

'You are my best friend. She's my sister. But neither of you told me. Not for a month.'

'I'm sorry, we didn't-'

'I hated her for it. That's the truth.'

She remembered sitting on the plaid sofa in their family home after learning their mother had cancer. Katie was crying heavy tears that soaked through the packet of tissues she carried in her handbag. Mia's eyes remained dry. When Finn arrived, he stood by the wood burner, the third corner of their awkward triangle, his foot jigging up and down as he listened to the prognosis. There was a moment when everything fell silent and his eyes flicked between them, not knowing who to comfort first: Katie, with her tear-stained face, or Mia with her flint-hard stare.

In the end he didn't have to choose: Mia had left the house, slamming the door so hard that the paintings rattled in their frames.

Now, Finn turned towards her. 'Mia, when I walk into a room, it's always you I see first.'

She could tell from the seriousness of his tone that he meant it. Meant something far more than she'd let herself see.

It wasn't Katie he saw first. It was her. Finn had always seen her, she realized.

Looking into his eyes she felt a dizzying rush of nostalgia, as if she were standing on the edge of their childhood and she could reach out and touch it run her fingers through years of shared memories, feel that easy happiness.

She could hear the waves breaking, see the glitter of the stars. The world was spinning and sliding away and she reached her hand to his arm, holding onto what was solid and firm. Then she leant towards him and placed her lips to his.

'Mia...'

She heard it in his voice he wanted this, had imagined it before. She kissed him again, deeply this time, as if she'd know herself better by sinking into him.

They lowered themselves onto his sleeping bag, the stars on her back. Her hair fell over her shoulders, brushing his face. She ran a hand towards the waist of his shorts and Finn caught it, lacing his fingers with hers. 'No, Mia. Not if you're unsure.'

There was rum warm in her stomach she knew that but there was something between them too. She didn't know what it was, she just knew she wanted it.

17.

KATIE.

Western Australia, June Katie read with her head bent over the journal, her right hand pressed to her mouth and her left hand gripping the table. She read what happened between Mia and Finn on a smooth, red rock where the waves growled through the night and the stars hung like golden orbs overhead. She read of an intimacy shared on a single sleeping bag that changed the shape of a friendship.

When she glanced up, she saw that the cafe was empty save for a waitress checking her phone with a private smile. Katie reached for her cappuccino: cold. A coffee machine with gleaming silver knobs had stopped whirring and beyond the cafe window the rush of traffic had slowed, and everything seemed changed. She looked back at the journal and understood now the depth of Mia's anger at her. But she couldn't regret what had happened between her and Finn. Not when those few months with him were among the happiest of her life.

Katie leant back in her chair, wondering, Was I that happy with Ed? He had returned to England three weeks ago, calling her several times a day to leave apologetic voicemails. Twice she had found herself dialling his number, lonely enough to want him back, but both times she had made herself ring Jess instead, who didn't hesitate in reminding her why the engagement was off.

Katie thought she'd been in love with Ed, but now she wondered whether what she had loved was actually the idea of their relationship. Ed was intelligent, charming and successful, but he had never surprised or challenged her. He'd never stayed up talking with her through the night. He'd never made her laugh so hard that her stomach ached.

She realized there was only one person who had.

Reading Mia's intimate journal entry about Finn had prised open Katie's own memories, which she wore pressed to her heart like a locket. Now she found herself slipping back in time as she let herself remember ...

Katie opened the lid of the cooling barbecue, then juggled the charred tinfoil packages onto a spare plate. Peeling back an edge she saw that the glossy kernels of corn had turned a rich gold. She offered one to her mother.

'I couldn't,' her mother said, placing the flat of her hand to her stomach.

'Mia?'

Mia shook her head as she sat cross-legged, dark glasses shading her eyes from the sun, hands wrapped around a mug of tea. The tea bothered Katie. Their garden table was still filled with home-made chilli burgers, chicken and cherry-tomato kebabs, crisped rosemary potatoes and half a jug of Pimm's. Their mother had spent the morning cooking to celebrate having both her daughters home for the weekend. If she was disappointed that Mia hadn't changed out of her pyjamas, she didn't show it.

Katie spread a knob of butter over one of the corncobs and bit into it, her mouth filling with the sweet, nutty taste.

'How is your head?' their mother asked Mia.

'Still there.'

'Where were you and Finn?'

'At the old quarry. Cliff party.'

'Ah,' their mother said, nodding, for cliff parties were known to involve a few hundred people, generators and decks, beer by the crate and a beach stroll home at dawn. 'I wish my headache was because of a cliff party, but I think I must be fighting off a bug. I'm going to lie down.'

Katie only managed half the corncob and then wiped the butter from her lips with a napkin.

Mia reached across the table and took Katie's left hand, pulling it towards her to inspect her nails. 'Have you had a manicure?'

'I was given a voucher.'

'It suits you,' she said, and Katie couldn't see her expression beneath her sunglasses.

Mia uncrossed her legs, rolled up her pyjama bottoms, and stretched her long legs across the picnic bench. 'God, it's good to feel the sun at last.'

Katie had a sudden desire to strip down to her underwear and lie in the spring sunshine with her sister, getting giddy on cocktails. It felt as though it had been months since they'd found the time to talk.

She fetched a picnic rug from the porch and put it down on the grass. 'Why don't I make us mojitos? Mum's got a bottle of white rum and there's fresh mint in the fridge.'

'I've got to drive back to uni soon.'

'You're going? You only arrived last night. It's a bank holiday tomorrow. I thought you were staying for the whole weekend.'

'I've got finals.'

'You're going back to revise? On a Sunday night?'

'I'm going back for a gig.'

Disappointed, Katie began clearing the plates, scraping the leftovers into a bowl and piling the cutlery on top.

The noise and activity seemed to aggravate Mia, who slipped from the table onto the freshly laid rug. She rolled up her T-shirt and flung her arms out at her sides.

'It'd be nice if you helped clear up.'

'I'll dry later.'

'You'll be gone later.'

'Before I go.'

'No, Mia. Now.'

She sat up. 'What is your problem?'

'Mum's been cooking all morning when she's not feeling-'

'I didn't ask her to.'

'It would be nice if you offered to help occasionally.'

'I can get you a badge that says perfect daughter. Will that help?'

'Maybe you'll get a discount if you order yourself shit sister.'

They glared at each other. Then Katie noticed Mia's lips turn up at the corners. 'You've got corn in your teeth,' Mia said, and they both laughed.