'Challenging, was the word he used.'

'Okay, okay, challenging. Along with every other five-year-old in the universe. It doesn't mean anyone would want to kill him.' And Mr Grant is a two-faced beardie freak, I add silently.

Kura stops walking. 'Then there's your husband, who seems to be avoiding contact with you, Finn or us.'

'Kit's overseas, for G.o.d's sake!'

'Martha.' She fixes me with a look of tragic disapproval. 'I don't think you've been straight with me. We've done some checks. A Christopher McNamara flew into Auckland from London late yesterday afternoon.'

The corridor turns into a swing boat. I find a low windowsill and sit down, breathing hard. Kura watches me.

'All right,' I say faintly. 'He drove home last night. He arrived at about ten, but we had a stupid row and he stormed off again. He was gone by half past.'

The social worker waits for a long time. When she speaks, her voice is too soft. 'What did you argue about?'

'That's absolutely none of your business.'

'Do you often have arguments?'

'No comment.'

She sighs.

'Just a minute.' She's only doing her job, and doing it well. I know this, but fear makes me belligerent. 'Excuse me, Kura. I have described exactly how Finn toppled off the balcony while he was sleepwalking. Are you calling me a liar?'

'No, Martha. I'm saying some of the indicators are there. So there are issues around child protection-'

'So you are calling me a liar.'

'-and we feel there should be a more detailed risk a.s.sessment.'

'I can't believe you people. Talk about shutting the stable door. Finn's life hangs in the balance, and you're doing risk a.s.sessments?'

'You have other children. Charlie and Sacha. Are they at risk? I've still got this feeling there are things you'd like to talk about.'

I think about Charlie and Sacha, left at Patupaiarehe, at risk. Kura is right: a part of me longs to tell her everything and beg for help. But I can't.

'Leave me alone.' I'm shouting now. People in the corridor look around. 'Leave my family alone!'

Kura is unmoved. 'I'm sorry. I can't do that.'

I get to my feet, giddy with terror. They'll take them all away, not only Finn. I'll lose my children. I turn my back and stagger away from her, faster and faster up the corridor.

'My door's open,' she calls after me. 'When you're ready.'

Back at Finn's side, I take out my phone. The battery's getting low. Soon it will be dead.

I call Kit's number. There's no answer, and a part of me is relieved. I've no idea what to say to him. I cannot envisage a future for us.

Thirty-one.

Expectations change; goalposts lower. I dream of my daughter becoming a concert flautist, a brilliant surgeon, a mother herself. I dream of my daughter conquering addiction. I dream of her living a normal life.

Sacha didn't even raise her head from the pillow when I looked in the next morning, though I chirruped like a fantail about what a lovely day it was. 'Beautiful,' I declared, drawing the curtains. 'Clear and blue from one horizon to the other. I'm just off to work.'

She lay without blinking. I sat down on the bed.

'How're you feeling?'

'Can't see the point.'

'Point of what?'

Long silence. 'Didn't my real father want me?'

For a wild moment, I thought about telling her who she was. Maybe she'd be healed and made whole by the knowledge; or maybe she'd be destroyed.

'He would be very proud of you, Sacha.'

'I think . . . maybe that's why you won't let me contact him. Did he want to get rid of me? Did he want me aborted?'

'No!' I was appalled. 'Truly, that isn't right at all.' I patted her knee where it stuck out from beneath the covers. 'Look, doll. The sky's blue. The gra.s.s is green. You're young and pretty and talented. You're going to have a wonderful life and bring happiness to lots of people.'

'I don't bring happiness.'

'Bianka phoned just now, worrying about you.'

This seemed to make matters even worse. A tear snaked down the side of Sacha's lifeless face and into lank hair. 'I don't deserve her.'

'C'mon, give yourself a shake. You've got so much; you're so lucky.'

'I know. I'm ungrateful.'

'There will be rules, of course, but we'll talk about those tonight. So- let's all move on! Shall we go away for a weekend? I thought we might drive up to Auckland to see the Russian Ice Dancers? We could even fly . . . I've got all those air points.'

Another tear roamed across her cheek.

'Jump up,' I said, giving her knee a final pat. 'Have some breakfast. Kit's in the studio.'

She shut her eyes, and I left her lying alone with the sky ablaze at her window.

She didn't get up. She fell into a bottomless well. For the next three days she slept like the dead. We had to force her to wash, to eat, to take care of herself at all. I began to fear she might try to take her own life, and had Kit checking her every hour. I used the fast internet at work to scroll through hundreds of websites, falling on any crumb of advice, learning about this venomous enemy.

There was a telephone helpline. I wrote the number down, but I never rang it. Sounds easy, doesn't it, just to dial a number? But believe me, it isn't easy. I seized up at the thought of discussing my Sacha with a stranger. I had this overwhelming terror that they would trace my number and turn up with flashing lights and handcuffs. For the same reasons, Kit and I decided not to seek professional help. Secret keeping becomes a habit.

The only bright point was that I managed to buy Sacha's flute back from the p.a.w.nbroker. It had sat unwanted on their shelf and they were happy to see the back of it. They made a hundred-dollar profit. 'Not much demand for flutes,' said the man, lugubriously. He reminded me of our one-armed petrol attendant. Perhaps everyone has a doppelganger in the opposite hemisphere.

Sibella was never seen again. Sacha said she'd given the painting to someone who paid her with a few crystals. We emailed a photo of the portrait to p.a.w.nbrokers and antiques shops, with no joy. Perhaps Sibella was lying among the rubbish in a sleazy flat; some junkie might have drawn a moustache and spectacles on her exquisite face.

Lou telephoned during this time. She sounded warm on the surface, but still-after almost a year-there was that chilly undercurrent of hurt.

I forced a smile into my voice. 'Big sis! How's life up top?'

So-so, apparently. Phil was applying for new jobs. 'And how's my darling Sacha?' she asked. 'Put her on!'

Her darling Sacha was curled foetally upstairs.

'Thriving,' I said firmly. 'But she's at orchestra practice.'

I didn't tell Dad either. Didn't even call him. I felt so horribly ashamed. In the end, he rang us.

'Everything all right?' he asked, in the first thirty seconds.

'Fine! Fine.'

He must have caught the bra.s.sy brightness because his voice sharpened suspiciously. 'Finn and Charlie?'

'Mad as hatters.'

'Kit?'

'Hard at work. Dublin exhibition coming up in August-three and a half months to go. He must be serious, because he's sworn off the booze until then.'

'Good Lord. Congratulate him from me! Sacha?'

'Well, she's been better. Just endless colds, you know. It's nearly winter here. And . . . well, maybe the first friends she picked turned out to be the wrong kind. She wasn't being bullied after all.'

'I'm pleased.' There was concern in his voice, but he didn't press for more detail. He's good like that. 'She hasn't replied to my last email. Tell her to write to old Pop.'

'Will do,' I promised, and changed the subject. We talked for ten minutes, and I suppose I made it all sound extra good.

'Lolling around the vineyards.' Dad chuckled. 'Life of Riley. You lot certainly have fallen on your feet.'

Mum popped up. Ha! You've fallen all right, but it isn't on your feet.

They say time is a great healer. Sacha's mood gradually lightened; after a fortnight she was back in school and keeping all our rules. She had pockmarks on her arms and hands, and I was sad to see that two sores around her mouth were slow to heal. I thought they might never quite disappear, but they could be covered with make-up. If they were the worst scars left by this evil, I told myself, she'd got off lightly.

Kit made a valiant effort to forgive his stepdaughter ('If I'm honest, I was a total k.n.o.b myself at her age') and focused on the exhibition. I loved him for that. He was getting through a lot of ginger beer. Bianka stuck by her friend, staying with us when she could. Life returned to normal. Almost normal.

In May, it began to rain. The duck hunting season was in full swing and volleys of gunfire echoed across the hills. This didn't go down well in our family.

'Those guys are either downright s.a.d.i.s.tic, or they're total tossing morons! Don't they know paradise ducks mate for life?' stormed Sacha. She and the boys painted a sign in red letters-NO SHOOTING!!!-and leaned it up at the road gate. Within hours, the word was out in the duck world. Skeins of them circled like jets waiting for permission to land, calling to their lifelong mates, swooping to the sanctuary of our dam.

Sacha seemed anxious to be a good sister again. One weekend when it rained so hard and so long that the paddock turned to mush, she taught the boys to play Monopoly; on a sunnier day, she and Bianka took them to the river where they made a miniature slipway. With the ceremonial cutting of a ribbon they launched boats made of ice-cream punnets and paper sails. I knew she was trying to make amends for the damage she'd caused, but I didn't mention it. There are some things better left unsaid, some memories that should be buried six feet under.

During June, the last copper leaves fell from the trees beside the drive and a gale blew them into swirls along the river bank. The boys rushed bright-faced through crackling drifts in their bare feet, screaming into the clean wind, throwing themselves on their backs with their arms flung out like gospel preachers. A shadow was lifting. We had a sense of darkness moving away.

July was mid-winter. We took the family skiing at Mount Ruapehu in the school holidays. It was a reward for us all, and a celebration. The twins, whose centre of gravity was about a foot off the ground, graduated from the nursery slope after two lessons. Finn was a fearless speed freak who spent half his time upended; Charlie had more sense. Like me, he meandered messily down the mountain, doing the side splits and getting in the way of hooded Neanderthal s...o...b..arders. Sacha had once been on a school ski trip to Austria. She and Kit explored the mountain together, and I gave her back her phone so we could stay in touch. By the third day, her face was burnished and her eyes glowed with their old life. One time when she and Kit were in the chair ahead of the rest of us, the lift stopped. I saw her rolling around, making their chair rock; I heard Kit pretending to squeal in fear, and Sacha's laughter glittering in the icy air. The malevolent spirit had lost, and we had won. His spell was broken. Sacha had escaped.

On the last afternoon I left Kit in charge of the boys. The lifts would soon close, and I was determined to ski right down the mountain without falling over. Reaching the crest of the last tow, I slid shambolically off my bar and almost collided with Sacha. 'Help,' I gasped, managing to stop beside her.

She'd pushed up her goggles and was gazing across at the perfect volcanic cone of Ngauruhoe, blinding white. Merry ringlets, each covered in a light frost, corkscrewed from under her cap. The peace was profound: just the clicking of the lift and a light wind blowing down our collars.

'Is this heaven?' she asked quietly.

'If heaven is half as heavenly as this, I might start going to church.'

'I don't think I'm going to heaven when I die.'

'Better not die, then.'

After a minute, she stirred. 'I stole from Bianka. I took her iPod and her phone. I emptied her father's wallet. She is the most loyal friend I've ever had, her mother is terribly ill, and I did that to her. I'm so going to h.e.l.l.'

'Is she more loyal than-say-Lydia?'

'Bianka's so deep. When she says she's your friend . . . well, it's a different kind of friendship. It's for life.'

'I'm sure she's forgiven you.'

'That's the awful thing. She has.'

Our breath clouded in the thin mountain air. People came up the lift and swept past us, but we didn't move.

'She left our party early,' I remembered.

'I was roaring that night, Mum. Absolutely roaring. Didn't you notice at all? Some of the guys were users, and we had our own party out in the hut.'

'Ed?'

'Yes, Ed does exist, and he did bring some with him-a birthday present for me. Bianka went mental and tried to take it off me. I screamed in her face and pushed her out of the door. I called her a c.u.n.t. I told her to get out of my life.'

'But those dull girls,' I said thoughtfully. 'They stayed.'

'Taylah and Teresa. Yes, Mum. The dull girls-has the penny finally dropped? It was them who gave me my first pipe, in a car at a fireworks party. Boring enough for you?'

I was shaken. 'They didn't look like drug pushers! Shouldn't we tell their parents?'

'Too late. Taylah's family threw her out. The last I heard she was selling s.e.x to gang members in return for drugs. Teresa got caught when the police raided a clan lab, so G.o.d knows where she is now. There was an anti-P campaigner came to our school. He said it's a five-year drug. In five years you'll be one of three things: locked up, covered up-that means dead-or sobered up. Not many people get sobered up. I'm lucky: I've been given a second chance, and there's no way I'm going to throw that chance away.'